Everyday Life Science Mysteries : Stories for Inquiry-Based Science Teaching [2 ed.] 9781938946950, 9781936959303

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Everyday life Science Mysteries

STORIES FOR INQUIRY-BASED SCIENCE TEACHING

How do tiny bugs get into oatmeal? What makes children look like—or different from—their parents? Where do rotten apples go after they fall off the tree? By presenting everyday mysteries like these, this book will motivate your students to carry out hands-on science investigations and actually care about the results. These 20 open-ended mysteries focus exclusively on biological science, including botany, human physiology, zoology, and health. The stories come with lists of science concepts to explore, grade-appropriate strategies for using them, and explanations of how the lessons align with national standards. They also relieve you of the tiring work of designing inquiry lessons from scratch.

STORIES FOR INQUIRY-BASED SCIENCE TEACHING

“What makes this book so special is the unique way science is integrated into the story line, using characters and situations children can easily identify with.”—Page Keeley, author of the NSTA Press series Uncovering Student Ideas in Science

PB333X2 ISBN: 978-1-936959-30-3

Grades K–8

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STORIES FOR INQUIRY-BASED SCIENCE TEACHING

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STORIES FOR INQUIRY-BASED SCIENCE TEACHING Richard Konicek-Moran, EdD Professor Emeritus University of Massachusetts Amherst Botanical illustrations by Kathleen Konicek-Moran

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Claire Reinburg, Director Jennifer Horak, Managing Editor Andrew Cooke, Senior Editor Wendy Rubin, Associate Editor Agnes Bannigan, Associate Editor Amy America, Book Acquisitions Coordinator

Art and Design Will Thomas Jr., Art Director Rashad Muhammad, Designer, cover and interior design Additional illustrations by D. W. Miller

Printing and Production Catherine Lorrain, Director

National Science Teachers Association David L. Evans, Executive Director David Beacom, Publisher 1840 Wilson Blvd., Arlington, VA 22201 www.nsta.org/store For customer service inquiries, please call 800-277-5300. Copyright © 2013 by the National Science Teachers Association. All rights reserved. Printed in the United States of America. 16 15 14 13   4 3 2 1 NSTA is committed to publishing material that promotes the best in inquiry-based science education. However, conditions of actual use may vary, and the safety procedures and practices described in this book are intended to serve only as a guide. Additional precautionary measures may be required. NSTA and the authors do not warrant or represent that the procedures and practices in this book meet any safety code or standard of federal, state, or local regulations. NSTA and the authors disclaim any liability for personal injury or damage to property arising out of or relating to the use of this book, including any of the recommendations, instructions, or materials contained therein. Permissions Book purchasers may photocopy, print, or e-mail up to five copies of an NSTA book chapter for personal use only; this does not include display or promotional use. Elementary, middle, and high school teachers may reproduce forms, sample documents, and single NSTA book chapters needed for classroom or noncommercial, professional-development use only. E-book buyers may download files to multiple personal devices but are prohibited from posting the files to third-party servers or websites or from passing files to non-buyers. For additional permission to photocopy or use material electronically from this NSTA Press book, please contact the Copyright Clearance Center (CCC) (www.copyright.com; 978-750-8400). Please access www.nsta.org/permissions for further information about NSTA’s rights and permissions policies.

Cataloging-in-Publication Data is available from the Library of Congress.

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CONTENTS

Acknowledgments................................................................................................................... vii Preface: Teaching and Interpreting Science............................................................................... ix Introduction: Case Studies on How to Use the Stories in the Classroom.................................. xi Chapter 1: Theory Behind the Book...................................................................................... 1 Chapter 2: Using the Book and the Stories............................................................................. 9 Chapter 3: Using this Book in Different Ways..................................................................... 17 Chapter 4: Science and Literacy........................................................................................... 27

The Stories and Background Materials for Teachers Chapter 5: Trees From Helicopters ...................................................................................... 43 (Botany: tree flowers) Chapter 6: Trees From Helicopters, Continued ................................................................... 53 (Botany) Chapter 7: Flowers: More Than Just Pretty .......................................................................... 65 (Botany) Chapter 8: Looking at Lichens ............................................................................................ 79 (Botany: symbiosis) Chapter 9: Seedlings in a Jar ............................................................................................... 91 (Botany: plant physiology) Chapter 10: Seed Bargains .................................................................................................. 101 (Botany: needs of seeds) Chapter 11: Springtime in the Greenhouse ......................................................................... 109 (Botany: needs of seeds) Chapter 12: Dried Apples ................................................................................................... 119 (Botany: water for life) Chapter 13: Plunk, Plunk ................................................................................................... 127 (Botany: imbibition, water) Chapter 14: Hitchhikers .................................................................................................... 139 (Botany: how seeds travel) Chapter 15: Halloween Science ........................................................................................... 149 (Pumpkin science) Chapter 16: In a Heartbeat ................................................................................................. 161 (Human physiology: circulation) Chapter 17: The Trouble With Bubble Gum ....................................................................... 171 (Health, nutrition) Chapter 18: About Me ........................................................................................................ 181 (Human physiology: genetics and inheritance) Chapter 19: A Tasteful Story ............................................................................................... 189 (Human biology: taste, bad science) Chapter 20: Reaction Time ................................................................................................. 201 (Human physiology: human reaction tests) Chapter 21: Worms Are for More Than Bait ....................................................................... 209 (Zoology: value of worms) Chapter 22: What Did That Owl Eat? ................................................................................ 219 (Zoology: exploring owl pellets) Chapter 23: Baking Bread ................................................................................................... 227 (Life science: yeast and leavening) Chapter 24: Oatmeal Bugs .................................................................................................. 237 (Entomology: life cycles of insects) Index..................................................................................................................................... 247 Copyright © 2013 NSTA. All rights reserved. For more information, go to www.nsta.org/permissions.

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Acknowledgments

I

would like to dedicate these stories and materials to the dedicated and talented teachers in the Springfield Public Schools in Springfield, Massachusetts. They have been my inspiration to produce materials that work with city as well as rural children. I would like to thank the following teachers, educators, and administrators who have helped me by field-testing the stories and ideas contained in this book over many years. These dedicated educators have helped me with their encouragement and constructive criticism: Richard Haller Jo Ann Hurley Lore Knaus Ron St. Amand Renee Lodi Deanna Suomala Louise Breton Ruth Chappel Theresa Williamson Third-grade team at Burgess Elementary in Sturbridge, Massachusetts Second-grade team at Burgess Elementary in Sturbridge, Massachusetts Fifth-grade team at Burgess Elementary in Sturbridge, Massachusetts Teachers at Millbury, Massachusetts, Elementary Schools Teachers and children at Pottinger Elementary School, Springfield, Massachusetts All the administrators and science specialists in the Springfield, Massachusetts, public schools, who are too numerous to mention individually

Jacobson who made it possible for me to find my place in teacher education at the university level. I also wish to thank Skip Snow, Jeff Kline, Jean and Rick Seavey and all of the biologists in the Everglades National Park with whom I have had the pleasure of working for the past 10 years for helping me to remember how to be a scientist again. And to the members of the interpretation groups in the Everglades National Park, at Shark Valley and Pine Island who helped me to realize again that it possible to help someone to look without telling them what to see and to help me to realize how important it is to guide people toward making emotional connections with our world. My sincere thanks goes to Claire Reinburg of NSTA who had the faith in my work to publish the original book and the second, third, and fourth volumes; and to Andrew Cooke, my editor, who helps me through the crucial steps. In addition I thank my lovely, brilliant, and talented wife, Kathleen, for her support, criticisms, illustrations, and draft editing. Finally I would like to dedicate these words to all of the children out there who love the world they live in and to the teachers and parents who help them to make sense of that world through the study of science.

My thanks also go out to all of the teachers and students in my graduate and undergraduate classes who wrote stories and tried them in their classes as well as using my stories in their classes. I will always be in the debt of my advisor at Columbia University, the late Professor Willard

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preface

P

erhaps because everyone has so much interaction with the biological world around them, most people feel fairly secure about teaching the biological sciences. Patterns, processes, and relationships among living things form the basis of biology, the study of life. Since biological beings can range from single cells to the entire biosphere, children must be prepared to study the relationships among the various organisms, populations, and ecosystems we find on Earth. And since so many of the organisms depend upon physical aspects of the environment, biology— like the other sciences—becomes multidisciplinary. They obey the laws of conservation of matter and energy (concepts found in physics) and engage in complex chemical reactions. They have evolved over eons and therefore are an integral part of the geological studies of the history of the Earth. In the stories in this volume, you will visit the areas of heredity, botany, zoology, reproduction, physiology, reaction time, food, and life cycles. All of these stories correspond with the scientific

principles, the crosscutting concepts, and the core ideas suggested and explained in the National Research Council’s A Framework for K–12 Science Education (2012). These stories are packaged in separate subject matter volumes so that those teachers who teach only one of the areas covered in these books can use them more economically. However, it bears repeating that the crosscutting concepts meld together the various principles of science across all disciplines. It is difficult, if not impossible, to teach about any scientific concept in isolation. Science is an equal opportunity field of endeavor, incorporating not only the frameworks and theories of its various specialties, but also its own structure and history. We hope that you will find these stories without endings a stimulating and provocative opening into the use of inquiry in your classrooms. Be sure to become acquainted with the stories in the other disciplinary volumes and endeavor to integrate all the scientific practices, crosscutting concepts, and core ideas that inquiry demands.

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Introduction Case Studies on How to Use the Stories in the Classroom

I would like to introduce you to one of the stories from the first volume of Everyday Science Mysteries (Konicek-Moran 2008) and then show how the story was used by two teachers, Teresa, a secondgrade teacher, and Lore, a fifth-grade teacher. Then in the following chapters I will explain the philosophy and organization of the book before going to the stories and background material. Here is the story, “Where Are the Acorns?”

Where Are the Acorns?

Cheeks looked out from her nest of leaves, high in the oak tree above the Anderson family’s backyard. It was early morning and the fog lay like a cotton quilt on the valley. Cheeks stretched her beautiful gray, furry body and looked about the nest. She felt the warm August morning air, fluffed up her big gray bushy tail and shook it. Cheeks was named by the Andersons since she always seemed to have her cheeks full of acorns as she wandered and scurried about the yard. “I have work to do today!” she thought and imagined the fat acorns to be gathered and stored for the coming of the cold times. Now the tough part for Cheeks was not gathering the fruits of the oak trees. There were plenty of trees and more than enough acorns for all of the gray squirrels who lived about the yard. No, the problem was finding them later on when the air was cold and the white stuff might be covering the lawn. Cheeks had a very good smeller and could sometimes smell the acorns she had buried earlier. But not always. She needed a way to remember where she had dug the holes and buried the acorns. Cheeks also had a very small memory and the yard

was very big. Remembering all of these holes she had dug was too much for her little brain. The Sun had by now risen in the East and Cheeks scurried down the tree to begin gathering and eating. She also had to make herself fat so that she would be warm and not hungry on long cold days and nights when there might be little to eat. “What to do ... what to do?” she thought as she wiggled and waved her tail. Then she saw it! A dark patch on the lawn. It was where the Sun did not shine. It had a shape and two ends. One end started where the tree trunk met the ground. The other end was lying on the ground a little ways from the trunk. “I know,” she thought. “I’ll bury my acorn out here in the yard, at the end of the dark shape and in the cold times, I’ll just come back here and dig it up! Brilliant Cheeks,” she thought to herself and began to gather and dig. On the next day she tried another dark shape and did the same thing. Then she ran about for weeks and gathered acorns to put in the ground. She was set for the cold times for sure! Months passed and the white stuff covered the ground and trees. Cheeks spent more time curled up in her home in the tree. Then one bright crisp morning, just as the Sun was lighting the sky, she looked down and saw the dark spots, brightly dark against the white ground. Suddenly she had a great appetite for a nice juicy acorn. “Oh yes,” she thought. “It is time to get some of those acorns I buried at the tip of the dark shapes.” She scampered down the tree and raced across the yard to the tip of the dark shape. As she ran, she tossed little clumps of white stuff into the air and they floated back onto the ground. “I’m so smart,” she thought to herself. “I know just where the acorns are.” She did seem to feel that she was a bit closer to the edge of the woods than she remembered but her memory was small and she ignored the feelings. Then she reached the end of the dark shape and began to dig and dig and dig! And she dug and she dug and she dug! Nothing! “Maybe I buried them a bit deeper,” she thought, a

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bit out of breath. So she dug deeper and deeper and still, nothing. She tried digging at the tip of another of the dark shapes and again found nothing. “But I know I put them here,” she cried. “Where could they be?” She was angry and confused. Did other squirrels dig them up? That was not fair. Did they just disappear? What about the dark shapes?

HOW TWO TEACHERS USED “WHERE ARE THE ACORNS?” Teresa, a veteran second-grade teacher

Teresa usually begins the school year with a unit on fall and change. This year she looked at the National Science Education Standards (NSES) and decided that a unit on the sky and cyclic changes would be in order. Since shadows were something that the children often noticed and included in playground games (shadow tag), Teresa thought using the story of Cheeks the squirrel would be appropriate. To begin, she felt that it was extremely important to know what the children already knew about the Sun and the shadows cast from objects. She wanted to know what kind of knowledge they shared with Cheeks and what kind of knowledge they had that the story’s hero did not have. She arranged the children in a circle so that they could see one another and hear one another’s comments. Teresa read the story to them, stopping along the way to see that they knew that Cheeks had made the decision on where to bury the acorns during the late summer and that the squirrel was looking for her buried food during the winter. She asked them to tell her what they thought they knew about the shadows that Cheeks had seen. She labeled a piece of chart paper, “Our best ideas so far.” As they told her what they “knew,” she recorded their statements in their own words:

“Shadows change every day.” “Shadows are longer in winter.” “Shadows are shorter in winter.” “Shadows get longer every day.” “Shadows get shorter every day.” “Shadows don’t change at all.” “Shadows aren’t out every day.” “Shadows move when you move.” She asked the students if it was okay to add a word or two to each of their statements so they could test them out. She turned their statements into questions and the list then looked like this: “Do shadows change every day?” “Are shadows longer in winter?” “Are shadows shorter in winter?” “Do shadows get longer every day?” “Do shadows get shorter every day?” “Do shadows change at all?” “Are shadows out every day?” “Do shadows move when you move? Teresa focused the class on the questions that could help solve Cheeks’s dilemma. The children picked “Are shadows longer or shorter in the winter?” and “Do shadows change at all?” The children were asked to make predictions based on their experiences. Some said that the shadows would get longer as we moved toward winter and some predicted the opposite. Even though there was a question as to whether they would change at all, they agreed unanimously that there would probably be some change over time. If they could get data to support that there was change, that question would be removed from the chart. Now the class had to find a way to answer their questions and test predictions. Teresa helped them talk about fair tests and asked them how they might go about answering the questions. They agreed almost at once that they should measure the shadow of a tree each day and write it down and should use the same tree and measure the shadow every day at the same time. They weren’t sure why time was important except that they said they wanted to make sure everything was fair. Even though data

xii

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about all of the questions would be useful, Teresa thought that at this stage, looking for more than one type of data might be overwhelming for her children. Teresa checked the terrain outside and realized that the shadows of most trees might get so long during the winter months that they would touch one of the buildings and become difficult to measure. That could be a learning experience but at the same time it would frustrate the children to have their investigation ruined after months of work. She decided to try to convince the children to use an artificial “tree” that was small enough to avoid our concern. To her surprise, there was no objection to substituting an artificial tree since, “If we measured that same tree every day, it would still be fair.” She made a tree out of a dowel that was about 15 cm tall and the children insisted that they glue a triangle on the top to make it look more like a tree. The class went outside as a group and chose a spot where the Sun shone without obstruction and took a measurement. Teresa was concerned that her students were not yet adept at using rulers and tape measures so she had the children measure the length of the shadow from the base of the tree to its tip with a piece of yarn and then glued that yarn onto a wall chart above the date when the measurement was taken. The children were delighted with this. For the first week, teams of three went out and took daily measurements. By the end of the week, Teresa noted that the day-to-day differences were so small that perhaps they should consider taking a measurement once a week. This worked much better, as the chart was less “busy” but still showed any important changes that might happen. As the weeks progressed, it became evident that the shadow was indeed getting longer each week. Teresa talked with the students about what would make a shadow get longer, and armed with flashlights, the children were able to make longer shadows of pencils by lowering the flashlight. The Sun must be getting lower too if this was the case, and this observation was added to

the chart of questions. Later, Teresa wished that she had asked the children to keep individual science notebooks so that she could have been more aware of how each individual child was viewing the experiment. The yarn chart showed the data clearly and the only question seemed to be, “How long will the shadow get?” Teresa revisited the Cheeks story and the children were able to point out that Cheeks’s acorns were probably much closer to the tree than the winter shadows indicated. Teresa went on with another unit on fall changes and each week added another piece of yarn to the chart. She was relieved that she could carry on two science units at once and still capture the children’s interest about the investigation each week after the measurement. After winter break, there was great excitement when the shadow began getting shorter. The shortening actually began at winter solstice around December 21 but the children were on break until after New Years. Now, the questions became “Will it keep getting shorter? For how long?” Winter passed and spring came and finally the end of the school year was approaching. Each week, the measurements were taken and each week a discussion was held on the meaning of the data. The chart was full of yarn strips and the pattern was obvious. The fall of last year had produced longer and longer shadow measurements until the New Year and then the shadows had begun to get shorter. “How short will they get?” and “Will they get down to nothing?” questions were added to the chart. During the last week of school, students talked about their conclusions and they were convinced that the Sun was lower and cast longer shadows during the fall to winter time and that after the new year, the Sun got higher in the sky and made the shadows shorter. They were also aware that the seasons were changing and that the higher Sun seemed to mean warmer weather and trees producing leaves. The students were ready to think about seasonal changes in the sky and relating them to seasonal cycles. At least Teresa thought they were.

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On the final meeting day in June, she asked her students what they thought the shadows would look like next September. After a great deal of thinking, they agreed that since the shadows were getting so short, that by next September, they would be gone or so short that they would be hard to measure. Oh my! The idea of a cycle had escaped them, and no wonder, since it hadn’t really been discussed. The obvious extrapolation of the chart would indicate that the trend of shorter shadows would continue. Teresa knew that she would not have a chance to continue the investigation next September but she might talk to the third-grade team and see if they would at least carry it on for a few weeks so that the children could see the repeat of the previous September data. Then the students might be ready to think more about seasonal changes and certainly their experience would be useful in the upper grades where seasons and the reasons for seasons would become a curricular issue. Despite these shortcomings, it was a marvelous experience and the children were given a great opportunity to design an investigation and collect data to answer their questions about the squirrel story at a level appropriate to their development. Teresa felt that the children had an opportunity to carry out a long-term investigation, gather data, and come up with conclusions along the way about Cheek’s dilemma. She felt also that the standard had been partially met or at least was in progress. She would talk with the thirdgrade team about that.

Lore (pronounced Laurie), a veteran fifth-grade teacher

In September while working in the school, I had gone to Lore’s fifth-grade class for advice. I read students the Cheeks story and asked them at which grade they thought it would be most appropriate. They agreed that it would most likely fly best at second grade. It seemed, with their advice, that Teresa’s decision to use it there was a good one. However, about a week after Teresa began to use the story, I received a note from Lore, telling

me that her students were asking her all sorts of questions about shadows, the Sun, and the seasons and asking if I could help. Despite their insistence that the story belonged in the second grade, the fifth graders were intrigued enough by the story to begin asking questions about shadows. We now had two classes interested in Cheeks’s dilemma but at two different developmental levels. The fifth graders were asking questions about daily shadows, direction of shadows, and seasonal shadows, and they were asking, “Why is this happening?” Lore wanted to use an inquiry approach to help them find answers to their questions but needed help. Even though the Cheeks story had opened the door to their curiosity, we agreed that perhaps a story about a pirate burying treasure in the same way Cheeks had buried acorns might be better suited to the fifth-grade interests in the future. Lore looked at the NSES for her grade level and saw that they called for observing and describing the Sun’s location and movements and studying natural objects in the sky and their patterns of movement. But the students’ questions, we felt, should lead the investigations. Lore was intrigued by the 5E approach to inquiry (engage, elaborate, explore, explain, and evaluate) and because the students were already “engaged,” she added the “elaborate” phase to find out what her students already knew. (The five Es will be defined in context as this vignette evolves.) So, Lore started her next class asking the students what they “knew” about the shadows that Cheeks used and what caused them. The students stated: “Shadows are long in the morning, short at midday, and longer again in the afternoon.” “There is no shadow at noon because the Sun is directly overhead.” “Shadows are in the same place every day so we can tell time by them.” “Shadows are shorter in the summer than in the winter.” “You can put a stick in the ground and tell time by its shadow.”

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Just as Teresa had done, Lore changed these statements to questions, and they entered the “exploration” phase of the 5E inquiry method. Luckily, Lore’s room opened out onto a grassy area that was always open to the Sun. The students made boards that were 30 cm2 and drilled holes in the middle and put a toothpick in the hole. They attached paper to the boards and drew shadow lines every half hour on the paper. They brought them in each afternoon and discussed their results. There were many discussions about whether or not it made a difference where they placed their boards from day to day. They were gathering so much data that it was becoming cumbersome. One student suggested that they use overhead transparencies to record shadow data and then overlay them to see what kind of changes occurred. Everyone agreed that it was a great idea. Lore introduced the class to the Old Farmer’s Almanac and the tables of sunsets, sunrises, and lengths of days. This led to an exciting activity one day that involved math. Lore asked them to look at the sunrise time and sunset time on one given day and to calculate the length of the daytime Sun hours. Calculations went on for a good 10 minutes and Lore asked each group to demonstrate how they had calculated the time to the class. There must have been at least six different methods used and most of them came up with a common answer. The students were amazed that so many different methods could produce the same answer. They also agreed that several of the methods were more efficient than others and finally agreed that using a 24-hour clock method was the easiest. Lore was ecstatic that they had created so many methods and was convinced that their understanding of time was enhanced by this revelation. This also showed that children are capable of metacognition—thinking about their thinking. Research tells us that elementary students are not astute at thinking about the way they reason but that they can learn to do so through practice and encouragement. Metacognition is important if

students are to engage in inquiry. They need to understand how they process information and how they learn. In this particular instance, Lore had the children explain how they came to their solution for the length-of-day problem so that they could be more aware of how they went about solving the challenge. Students can also learn about their thinking processes from peers who are more likely to be at the same developmental level. Discussions in small groups or as an entire class can provide opportunities for the teacher to probe for more depth in student explanations. The teacher can ask the students who explain their technique to be more specific about how they used their thought processes: dead ends as well as successes. Students can also learn more about their metacognitive processes by writing in their notebooks about how they thought through their problem and found a solution. Talking about their thinking or explaining their methods of problem solving in writing can lead to a better understanding of how they can use reasoning skills better in future situations. I should mention here that Lore went on to teach other units in science while the students continued to gather their data. She would come back to the unit periodically for a day or two so the children could process their findings. After a few months, the students were ready to get some help in finding a model that explained their data. Lore gave them globes and clay so that they could place their observers at their latitude on the globe. They used flashlights to replicate their findings. Since all globes are automatically tilted at a 23.5-degree angle, it raised the question as to why globes were made that way. It was time for the “explanation” part of the lesson and Lore helped them to see how the tilt of the Earth could help them make sense of their experiences with the shadows and the Sun’s apparent motion in the sky. The students made posters explaining how the seasons could be explained by the tilt of the Earth and the Earth’s revolution around the Sun each year. They had “evaluated” their understanding and

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“extended” it beyond their experience. It was, Lore agreed, a very successful “6E” experience. It had included the engage, elaborate, explore, explain, and evaluate phases, and the added extend phase.

References Konicek-Moran, R. 2008. Everyday science mysteries. Arlington, VA: NSTA Press.

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Chapter 1

THEORY BEHIND the BOOK

W

e have all heard people refer to any activity that takes place in a science lesson as an “experiment.” Actually, as science is taught today, true experiments are practically nonexistent. Experiments by definition test hypotheses, which are themselves virtually nonexistent in school science. A hypothesis, a necessary ingredient in any experiment, is a human creation developed by a person who has been immersed in a problem for a sufficient amount of time to feel the need to come up with a theory to explain events over which he or she has been puzzled. However, it is quite common and proper for us to investigate our questions without proper hypotheses. Investigations can be carried out as “fair tests,” which are possibly more appropriate for elementary classrooms, where children often lack the experience of creating a hypothesis in the true scientific mode. I recently asked a fourth-grade girl what a “fair experiment” was and she replied, “It’s an experiment where the answer is the one I expected.” We cannot assume even at the fourth-grade level students are comfortable with controlling variables; it needs repeating. A hypothesis is more than a guess. It will most often contain an “if… then…” statement, such as, “If I put a thermometer in a mitten and the temperature stays the same, then perhaps the mitten did not produce heat.” In school science, predictions should also be more than mere guesses or hunches, but rather based on experience and thoughtful consideration. Consistently asking children to give reasons for their predictions is a good

way to help them see the difference between guessing and predicting. Two elements are often missing in most school science curricula: sufficient time to puzzle over problems that have some real-life applications. It is much more likely that students will use a predetermined amount of time to “cover” an area of study—pond life, for example—with readings, demonstrations, and a field trip to a pond with an expert, topped off with individual or group reports on various pond animals and plants, complete with shoe box dioramas and giant posters. Or there may be a study of the solar system, with reports on facts about the planets and culminating with a class model of the solar system hung from the ceiling. These are naturally fun to do, but the issue is that there are seldom any real problems—nothing into which the students can sink their collective teeth into and use their minds to ponder, puzzle, hypothesize, and experiment. You have certainly noticed that most science curricula have a series of “critical” activities in which students participate that supposedly lead to an understanding of a particular concept. In most cases, there is an assumption that students enter the study of a new unit with a common view or a common set of preconceptions about certain concepts and the activities will move the students closer to the accepted scientific view. This is a particularly dangerous assumption, since research shows that students enter into learning situations with a variety of preconceptions. These preconceptions are not only well ingrained in the students’ minds but are exceptionally resistant to change. Going through the

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series of prescribed activities will have little meaning to students who have preconceptions that have little connection to the planned lessons, especially if the preconceptions are not recognized or addressed. Bonnie Shapiro, in her book, What Children Bring to Light (1994), points out in indisputable detail how a well-meaning science teacher ran his students through a series of activities on the nature of light without knowing that the students in the class all shared the misconception that seeing any object originates in the eye of the viewer and not from the reflection of light from an object into the eye. The activities were, for all intents and purposes, wasted, although the students had “solved the teacher” to the extent that they were able to fill in the worksheets and pass the test at the end of the unit—all the while doubting the critical concept that light reflecting from object to eye was the paramount fact and meaning of the act of seeing. Solving the teacher means that the students have learned a teacher’s mannerisms, techniques, speech patterns, and teaching methods to the point that they can predict exactly what the teacher wants, what pleases or annoys her, and how to perform so the teacher believes her students have learned and understood the concepts she attempted to teach. In her monograph Inventing Density (1986), Eleanor Duckworth says, “The critical experiments themselves cannot impose their own meanings. One has to have done a major part of the work already. One has to have developed a network of ideas in which to imbed the experiments.” This may be the most important quote in this book! How does a teacher make sure students develop a network of ideas in which to imbed the class activities? How does the teacher uncover student misconceptions about the topic to be studied? I believe that this book can offer some answers to these questions and offer some suggestions for remedying the problems mentioned above.

What Is Inquiry, Anyway? There is probably no one definition of “teaching for inquiry,” but at this time the

acknowledged authorities on this topic have to be the National Research Council (NRC) and the American Association for the Advancement of Science (AAAS). After all, they are respectively the authors of the National Science Education Standards (1996) and the Benchmarks for Science Literacy (1993), upon which most states have based their curriculum standards. For this reason, I will use their definition, which I will follow throughout the book. The NRC, in Inquiry and the National Science Education Standards: A Guide for Teaching and Learning (2000), says that for real inquiry to take place in the classroom, the following five essentials must occur: • • • • •

Learner engages in scientifically oriented questions. Learner gives priority to evidence in responding to questions. Learner formulates explanations from evidence. Learner connects explanations to scientific knowledge. Learner communicates and justifies explanations. (p. 29)

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In essence the NRC strives to encourage more learner self-direction and less direction from the teacher as time goes on during the school years. The NRC also make it very clear that all science cannot be taught in this fashion. Science teaching that uses a variety of strategies is less apt to bore students and be more effective. Giving demonstrations, leading discussions, solving presented problems, and entering into a productive discourse about science are all viable alternatives. However, the NRC does suggest that certain common components should be shared by whichever instructional model is used: • Students are involved with a scientific question, event, or phenomenon which connects with what they already know and creates a dissonance with their own ideas. In other words, they confront their preconceptions through an involvement with phenomena. • Students have direct contact with materials, formulate hypotheses, test them and create explanations for what they have found. • Students analyze and interpret data, and come up with models and explanations from these data. • Students apply their new knowledge to new situations. • Students engage in metacognition, thinking about their thinking, and review what they have learned and how they have learned it. You will find opportunities to do all of the above by using these stories as motivators for your students to engage in inquiry-based science learning.

THE REASONS FOR THIS BOOK According to a summary of current thinking in science education in the jour-

nal Science Education, “one result seems to be consistently demonstrated: students leave science classes with more positive attitudes about science (and their concepts of themselves as science participants) when they learn science through inductive, hands-on techniques in classrooms where they’re encouraged by a caring adult and allowed to process the information they have learned with their peers” (1993). This book, and particularly the stories that lie within, provide an opportunity for students to take ownership of their learning and as stated in the quotation above, learn science in a way that will give them a more positive attitude about science and to process their learning with their classmates and teachers. Used as intended, the stories will require group discussions, hands-on and minds-on techniques, and a caring adult.

THE STORIES These stories are similar to mystery tales but purposely lack the final chapter where

the clever sleuth finally solves the mystery and tells the readers not only “whodunit,” but how she knew. Because of the design of the tales in this book, the

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Chapter 1

students are challenged to become the sleuths and come up with likely “suspects” (the hypotheses or predictions) and carry out investigations (the experiments or investigations) to find out “whodunit” (the results). In other words, they write the final ending or perhaps endings. They are placed in a situation where they develop, from the beginning, “the network of ideas in which to imbed activities,” as Duckworth suggests (1986, p. 39). The students are also the designers of the activities and therefore have invested themselves in finding the outcomes that make sense to them. I want them to have solved the problem rather than having solved the teacher. I do want to reemphasize, however, that we should all be aware that successful students do spend energy in solving their teachers. In one story (“Seedlings in a Jar,” chapter 9), Sara and Ina are puzzled by the results of the experiment of planting seeds in a closed jar. They need to consider the differences between closed and open systems. Truly this is science as process and product. It also means that the students “own” the problem. This is what we mean by “hands-on, minds-on” science instruction. The teachers’ belief in the ability of their students to own the questions and to carry out the experiments to reach conclusions, is paramount to the process. Each story has suggestions as to how the teachers can move from the story reading to the development of the problems, the development of the hypotheses and eventually the investigations that will help their students to come to conclusions. Learning science through inquiry is a primary principle in education today. You might well ask, “instead of what?” Well, instead of learning science as a static or unchanging set of facts, ideas, and principles without any attention being paid to how these ideas and principles were developed. Obviously, we cannot expect our students to discover all of the current scientific models and concepts. We do however, expect them to appreciate the processes through which the principles are attained and verified. We also want them to see that science includes more than just what occurs in a classroom; that the everyday happenings of their lives are connected to science. Exploring the implications of friction, trying to repair a crooked garden swing, or wondering about how seeds can grow in a closed jar are only some of the examples of everyday life connected to science as a way of thinking and as a way of constructing new understandings about our world. There are 15 stories in this book, each one focused on a particular conceptual area, such as thermodynamics, heat energy, melting or dissolving, the chemistry of cooking, astronomy, decomposition, and determining differences in reaction time. Each story can be photocopied and distributed to students to read and discuss or they can be read aloud to students and discussed by the entire class. During the discussion, it is ultimately the role of the teacher to help the students to find the problem or problems and then design ways to find out answers to the questions they have raised. Most stories also include a few “distractors,” also known as common misconceptions or alternative conceptions. The distractors are usually placed in the stories as opinions voiced by the characters who discuss the problematic situation. For example, in “Springtime in the Greenhouse,” family members argue over what is

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necessary for seeds to germinate. Each family member has his or her own preconception or misconception. The identification of these misconceptions is the product of years of research, and the literature documents the most common, often shared by both children and adults. Where do these common misconceptions come from and how do they arise?

DEVELOPMENT OF MENTAL MODELS Until recently, educational practice has operated under the impression that chil-

dren and adults come to any new learning situation without the benefit of prior ideas connected to the new situation. Research has shown that in almost every circumstance, learners have developed models in their mind to explain many of the everyday experiences they have encountered (Bransford, Brown, and Cocking 1999; Watson and Konicek 1990; Osborne and Fryberg 1985). Everyone has had experience with differences in temperature as they place their hands on various objects. Everyone has seen objects in motion and certainly has been in motion, either in a car, plane, or bicycle. Everyone has experienced forces in action, upon objects or upon themselves. Finally, each of us has been seduced into developing a satisfactory way to explain these experiences and to have developed a mental model, which explains these happenings to our personal satisfaction. Probably, most individuals have read books, watched programs on TV or in movie theaters, and used these presented images and ideas to embellish their personal models. It is even more likely that they have been in classrooms where these ideas have been discussed by a teacher or by other students. The film A Private Universe (Schneps 1987) documents that almost all of the interviewed graduates and faculty of Harvard University showed some misunderstanding for either the reasons for the seasons, or for the reasons for the phases of the Moon. Many had taken high-level science courses either in high school or at the university. According to the dominant and current learning theory called constructivism, all of life’s experiences are integrated into the person’s mind; they are accepted or rejected or even modified to fit existing models residing in that person’s mind. Then, these models are used and tested for their usefulness in predicting outcomes experienced in the environment. If a model works, it is accepted as a plausible explanation; if not, it is modified until it does fit the situations one experiences. Regardless, these models are present in everyone’s minds and brought to consciousness when new ideas are encountered. They may be in tune with current scientific thinking but more often they are “common sense science” and not clearly consistent with current scientific beliefs. One of the reasons for this is that scientific ideas are often counterintuitive to everyday thinking. For example, when you place your hand on a piece of metal in a room, it feels cool to your touch. When you place your hand on a piece of wood in the same room it feels warmer to the touch. Many people will deduce that the temperature of the metal is cooler than that of the wood. Yet, if the objects have

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Chapter 1

been in the same room for any length of time, their temperatures will be equal. It turns out that when you place your hand on the metal, it conducts heat out of your hand quickly, thus giving the impression that it is cold. The wood does not conduct heat as rapidly as the metal and therefore feels warmer than the metal. In other words, our senses have fooled us into thinking that instead of everything in the room being at room temperature, the metal is cooler than anything else. Therefore our erroneous conclusion is that metal objects are always cooler than other objects in a room. Indeed, if you go from room to room and touch many objects, your idea is reinforced and becomes more and more resistant to change. These ideas are called by many names: misconceptions, prior conceptions, children’s thinking, or common sense ideas. They all have two things in common. They are usually firmly embedded in the mind, and they are highly resistant to change. Finally, if allowed to remain unchallenged, these ideas will dominate a student’s thinking, for example, about heat transfer, to the point that the scientific explanation will be rejected completely regardless of the method by which it is presented. Our first impression is that these preconceptions are useless and must be quashed as quickly as possible. However, they are useful since they are the precursors of new thoughts and should be modified slowly toward the accepted scientific thinking. New ideas will replace old ideas only when the learner becomes dissatisfied with the old idea and realizes that a new idea works better than the old. It is our role to challenge these preconceptions and move learners to consider new ways of looking at their explanations and to seek ideas that work in broader contexts with more reliable results.

WHY STORIES? Why stories? Primarily, stories are a very effective way to get someone’s attention.

Stories have been used since the beginning of recorded history and probably long before that. Myths, epics, oral histories, ballads, dances, and such have enabled humankind to pass on the culture of one generation to the next, and the next, ad infinitum. Anyone who has witnessed story time in classrooms, libraries, or at bedtime knows the magic held in a well-written, well-told tale. They have beginnings, middles, and ends. These stories begin like many familiar tales do: in homes or classrooms; with children interacting with siblings, classmates, or friends; with parents or other adults in family situations. But here the resemblance ends between our stories and traditional ones. Science stories normally have a theme or a scientific topic that unfolds giving a myriad of facts, principles and perhaps a set of illustrations or photographs, which try to explain to a child the current understanding about the given topic. For years science books have been written as reviews of what science has constructed to the present. These books have their place in education, even though children often get the impression from these books that the information they have just read

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about appeared magically as scientists went about their work and “discovered” truths and facts depicted in those pages. But as Martin and Miller (1990) put it: “The scientist seeks more than isolated facts from nature. The scientist seeks a story [emphasis mine]. Inevitably the story is characterized by a mystery [emphasis mine]. Since the world does not yield its secrets easily, the scientist must be a careful and persistent observer.” As our tales unfold, discrepant events and unexpected results tickle the characters in the stories and stimulate their wonder centers making them ask, “What's going on here?” Most important of all, our stories have endings that are different than most. They are the mysteries that Martin and Miller talk about. They end with an invitation to explore and extend the story and to engage in inquiry. These stories do not come with built-in experts who eventually solve the problem and expound on the solution. There is no Doctor Science who sets everybody straight in short order. Moms, dads, big sisters, brothers, and friends may offer opinionated suggestions ripe for consideration, or tests to be designed and carried out. It is the readers who are invited to become the scientists and solve the problem.

References American Association for the Advancement of Science (AAAS).1993. Benchmarks for science literacy. New York: Oxford University Press. Bransford, J. D., A. L. Brown, and R. R. Cocking, eds. 1999. How people learn. Washington, DC: National Academies Press. Duckworth, E. 1986. Inventing density. Grand Forks, ND: Center for Teaching and Learning, University of North Dakota. Martin, K., and E. Miller. 1990. Storytelling and science. In Toward a whole language classroom: Articles from language arts, 1986–1989, ed. B. Kiefer. Urbana, IL: National Council of Teachers of English. National Research Council (NRC). 2000. Inquiry and the national science education standards: A guide for teaching and learning. Washington, DC: National Academies Press. Osborne, R., and P. Fryberg. 1985, Learning in science: The implications of children’s science. Auckland, New Zealand: Heinemann. Schneps, M. A. 1996. The private universe project. Harvard Smithsonian Center for Astrophysics. Shapiro, B. 1994. What children bring to light. New York: Teachers College Press. Watson, B., and R. Konicek. 1990, Teaching for conceptual change: Confronting children’s experience. Phi Delta Kappan 71 (9): 680–684.

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Chapter 1

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Chapter 2

USING the BOOK and the STORIES

I

t is often difficult for overburdened teachers to develop lessons or activities that are compatible with the everyday life experiences of their students. A major premise of this book is that if students can see the real-life implications of science content, they will be motivated to carry out hands-on, mindson science investigations and personally care about the results. Science educators have, for decades, emphasized the importance of science experiences for students that emphasize personal involvement in the learning process. I firmly believe that the use of open-ended stories that challenge students to engage in real experimentation about real science content can be a step toward this goal. Furthermore, I believe that students who see a purpose to their learning and experimentation are more likely to understand the concepts they are studying. I sincerely hope that the contents of this book will relieve the overburdened teacher from the exhausting work of designing inquiry lessons from scratch. These stories feature children in natural situations at home, on the playground, at parties, in school, or in the outdoors. Students should identify with the story

characters, to share their frustrations, concerns, and questions. The most important role for the adult is to help guide and facilitate investigations and to debrief activities with them and to think about their analyses of results and conclusions. The children often need help to go to the next level and to develop new questions and find ways of following these questions to a conclusion. Our philosophy of science education is based on the belief that children can and want to care enough about problems to make them their own. This should enhance and invigorate any curriculum. In short, students can begin to lead the curriculum and because of their personal interest in the questions that evolve from their activities, they will maintain interest for much longer than they would if they were following someone else’s lead. A teacher told me that one of her biggest problems is to get her students to “care” about the topics they are studying. She says they go through the motions but without affect. Perhaps this same problem is familiar to you. I hope that this book can help you to take a step toward solving that problem. It is difficult if not impossible to make each lesson personally relevant to

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every student. However, by focusing on everyday situations and highlighting kids looking at everyday phenomena, I believe that we can come closer to reaching student interests. I strongly suggest the use of complementary books as you go about planning for inquiry teaching. Five special books are Uncovering Student Ideas (volumes 1, 2, 3, and 4) by Page Keeley et al., published by the NSTA Press and Science Curriculum Topic Study by Page Keeley, published by Corwin Press and NSTA. The multivolume Uncovering Student Ideas helps you to find out what kinds of preconceptions your students bring to your class. Science Curriculum Topic Study focuses on finding the background necessary to plan a successful standards-based unit. I would also strongly recommend that you find a copy of Science Matters: Achieving Scientific Literacy, by Robert Hazen and James Trefil. This book will become your reference for many scientific matters. It is written in a simple, direct and accurate manner and will give you the necessary background in the sciences when you need it. Finally please acquaint yourself with Making Sense of Secondary Science: Research Into Children’s Ideas (Driver et al. 1994). The title of this book can be misleading to American teachers, because in Great Britain, anything above primary level is referred to as secondary. It is a compilation of the research done on children’s thinking about science and is a must-have for teachers. Use it as a reference in looking for the preconceptions your students probably bring to your classroom. In 1978, David Ausubel made one of the most simple but telling comments about teaching: “The most important single factor influencing learning is what the learner already knows; ascertain this, and teach him accordingly.” The background material that accompanies each story is designed to help you to find out what your learners already know about your chosen topic and what to do with that knowledge as you plan. The above-mentioned books will supplement the materials in this book and deepen your understanding of teaching for inquiry. How then, is this book set up to help you to plan and teach inquiry-based science lessons?

HOW THIS BOOK IS ORGANIZED There is a concept matrix (p. 41) that can be used to select a story most related to

your content need. Following this matrix you will find the stories and the background material in separate chapters. Each chapter, starting with Chapter 5, will have the same organizational format. First you will find the story, followed by background material for using the story. The background material will contain the following sections:

Purpose

This section describes the concepts and/or general topic that the story attempts to address. In short, it tells you where this story fits into the general scheme of science concepts. It may also place the concepts within a conceptual scheme of a larger idea.

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Related Concepts

A concept is a word or combination of words that form a mental construct of an idea. Examples are diversity, pollination, senses, and germination. Each story is designed to address a single concept but often the stories open the door to several concepts. You will find a list of possible related concepts in the teacher background material. You should also check the matrix of stories and related concepts.

Chapter 2

Don’t Be Surprised

In most cases, this section will include projections of what your students will most likely do and how they may respond to the story. The projections relate to the content but focus more on the development of their current understanding of the concept. The explanation will be related to the content but will focus more on the development of the understanding of the concept. There will be references made to the current alternative conceptions your students might be expected to bring to class. It may even challenge you to prepare for teaching by doing some of the projected activities yourself, so that you are prepared for what your students will bring to class.

Content Background

This material will be a very succinct “short course” on the conceptual material that the story targets. It will not, of course, be a complete coverage but should give you enough information to feel comfortable in using the story and planning and carrying out the lessons. In most instances, references to books, articles, and internet connections will also help you in preparing yourself to teach the topic. It is important that you have a reasonable knowledge of the topic in order for you to lead the students through their inquiry. It is not necessary, however, for you to be an expert on the topic. Learning along with your students can help you to understand how their learning takes place and make you a member of the class team striving for understanding of natural phenomena. Table 2.1. Thematic Crossover Between Stories in This Book and Uncovering Student Ideas in Science, Volumes 1–4 Story in this book Trees From Helicopters Flowers: More Than Just Pretty Looking at Lichens

Uncovering Student Ideas in Science Volume 1 Volume 2 Volume 3 Volume 4 n/a Needs of Seeds; Where Do Seeds Biological Is It a Plant? Come From? Evolution Is It a Plant? Does It Have a Biological Seedlings in a Life Cycle? Evolution Jar; Functions of Living Things n/a Is It a Plant? Does It Have a Is It “Fitter?” Life Cycle? Respiration (continued on next page)

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(continued from previous page) Story in this book

Uncovering Student Ideas in Science Volume 1 Volume 2 Volume 3 Is It Food for Does It Have a Seedlings In a Jar Functions of Plants? Life Cycle? Living Things; Seedlings in a Jar Seed Bargains Is It Living? Needs of Seeds Where Do Seeds Come From? Doing Science; Springtime in the Seedlings in a Jar Is It a Plant? Greenhouse Needs of Seeds; What Is a Hypothesis? Is It Food for Does It Have a Plants? Life Cycle? Respiration Dried Apples Is It Made of n/a Where Does It Cells? Go? Doing Science; Plunk, Plunk Seedlings in a Jar Is It a Plant? What Is a Is It Food for Hypothesis? Plants? Does It Have a Life Cycle? Respiration Hitchhikers Functions of n/a Does It Have a Living Things Life Cycle? Doing Science; Halloween Is It Living? Is It a Plant? Science Needs of Seeds; What Is a Hypothesis? Is It Food for Does It Have a Plants? Life Cycle? In a Heartbeat Human Body n/a Doing Science; Basics What Is a Hypothesis? The Trouble With n/a n/a Doing Science; Bubble Gum What Is a Hypothesis? About Me n/a Baby Mice n/a

Volume 4 Is It a System?

Is It Food?

Is It Food?

Biological Evolution Is It Food?

Adaptation; Is It “Fitter?” Adaptation; Is It “Fitter?”

Is It a System?

Is It Food?

Biological Evolution

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Story in this book A Tasteful Story

Reaction Time

Uncovering Student Ideas in Science Volume 1 Volume 2 Volume 3 Volume 4 n/a n/a Is It Food? Human Body Basics; Functions of Living Things n/a Doing Science; Is It a System? Human What Is a Body Basics; Hypothesis? Functions of Living Things

Worms Are For More Than Bait What Did That Owl Eat? Baking Bread

Is It an Animal? Is It Living? Is It an Animal? Is It Living? n/a

Oatmeal Bugs

Is It an Animal? Is It Living?

Is It Food for Plants? Habitat Change

Does It Have a Biological Life Cycle? Evolution n/a Is It Food? Is It a System? Chemical Bonds Doing Science; Is It Food? Is It a System? What Is a Hypothesis? Respiration n/a Does It Have a Biological Life Cycle? Evolution

Related Ideas from the National Science Education Standards (NRC 1996) and Benchmarks for Science Literacy (AAAS 1993)

These two documents are considered to be the National Standards upon which most of the local and state standards documents are based. For this reason, the concepts listed for the stories are almost certainly the ones listed to be taught in your local curriculum. It is possible that some of the concepts are not mentioned specifically in the Standards but are clearly related. I suggest that you obtain a copy of Curriculum Topic Study (Keeley 2005), which will help you immensely with finding information about content, children’s preconceptions, standards, and more resources. Even though it may not be mentioned specifically in each of the stories, you can assume that all of the stories will have connections to the Standards and Benchmarks in the area of Inquiry, Standard A.

Using the Story With Grades K–4 and 5–8

These stories have been tried with children of all ages. We have found that the concepts apply to all grade levels but at different levels of sophistication. Some of the characters in the stories have themes and characters that resonate better with one age group than

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Chapter 2

another. However, the stories can be easily altered to appeal to an older or younger group by changing the characters to a more appropriate age or using slightly different age-appropriate dialog. The theme should be the same; just the characters and setting modified. Please read the suggestions for both grade levels. As you may remember from the case study in the introduction, grade level is of little consequence in determining which stories are appropriate at which grade level. Both classes developed hypotheses and experiments appropriate to their developmental abilities. Second graders were satisfied to find out what happens to the length of a tree’s shadow over a school year while the fifth grade class developed more sophisticated experiments involving length of day, direction of shadows over time, and the daily length of shadows over an entire year. The main point here is that by necessity some stories are written with characters more appealing to certain age groups than others. Once again, I encourage you to read both the K–4 and 5–8 sections of Using the Story because ideas presented for either grade level may be suited to your particular students. There is no highly technical apparatus required. Readily available materials found in the kitchen, bathroom, or garage will usually suffice. Each chapter includes background information about the principles and concepts involved and a list of materials you might want to have available. These suggestions of ideas and materials are based upon our experience while testing these stories with children. While we know that classrooms, schools, and children differ, we feel that most childhood experiences and development result in similar reactions to explaining and developing questions about the tales. The problems beg for solutions and most importantly, create new questions to be explored by your young scientists. Here you will find suggestions to help you teach the lessons that will allow your students to become active inquirers, develop their hypotheses, and finally finish the story that you may remember was left open for just this purpose. I have not listed a step-by-step approach or set of lesson plans to accomplish this end. Obviously, you know your students, their abilities, their developmental levels, and their learning abilities and disabilities better than anyone. You will find, however, some suggestions and some techniques that we have found work well in teaching for inquiry. You may use them as written or modify them to fit your particular situation. The main point is that you try to involve your students as deeply as possible in trying to solve the mysteries posed by the stories.

Related Books and NSTA Journal Articles

Here, we will list specific books and articles from the constantly growing treasure trove of National Science Teacher Association (NSTA) resources for teachers. While our listings are not completely inclusive, you may access the entire scope of resources on the internet at www.nsta.org/store. Membership in NSTA will allow you to read all articles online free of charge.

References

References will be provided for the articles and research findings cited in the background section for each story.

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Concept Matrix

At the beginning of the story section you will find a concept matrix listing the concepts most related to each story. It can be used to select a story that matches your instructional needs.

FINAL WORDS I was pleased to find that Michael Padilla, past president of NSTA, asked the same

questions as I did when I decided to write a book that focused on inquiry. In the May 2006 edition of NSTA Reports, Mr. Padilla in his “President’s Message” commented, “To be competitive in the future, students must be able to think creatively, solve problems, reason and learn new, complex ideas… [Inquiry] is the ability to think like a scientist, to identify critical questions to study; to carry out complicated procedures, to eliminate all possibilities except the one under study; to discuss, share and argue with colleagues; and to adjust what you know based on that social interaction.” Further, he asks, “Who asks the question?...Who designs the procedures?...Who decides which data to collect?...Who formulates explanations based upon the data?...Who communicates and justifies the results?...What kind of classroom climate allows students to wrestle with the difficult questions posed during a good inquiry?” I believe that this book speaks to these questions and that the techniques proposed here are one way to answer the above questions with, “The students do!” in the kind of science classroom this book envisions.

REFERENCES Ausubel, D., J. Novak, and H. Hanensian. 1978. Educational psychology: A cognitive view. New York: Holt, Rinehart, and Winston. Driver, R., A. Squires, P. Rushworth, and V. Wood-Robinson. 1994. Making sense of secondary science: Research into children’s ideas. London and New York: Routledge Falmer. Hazen, R., and J. Trefil. 1991. Science matters: Achieving scientific literacy. New York: Anchor Books. Keeley, P. 2005. Science curriculum topic study: Bridging the gap between standards and practice. Thousand Oaks, CA: Corwin Press. Keeley, P., F. Eberle, and C. Dorsey. 2008. Uncovering student ideas in science, volume 3: Another 25 formative assessment probes. Arlington, VA: NSTA Press. Keeley, P., F. Eberle, and L. Farrin. 2005. Uncovering student ideas in science, volume 1: 25 formative assessment probes. Arlington, VA: NSTA Press. Keeley, P., F. Eberle, and J. Tugel. 2007. Uncovering student ideas in science, volume 2: 25 more formative assessment probes. Arlington, VA: NSTA Press. Keeley, P., and J. Tugel. 2009. Uncovering student ideas in science, volume 4: 25 new formative assessment probes. Arlington, VA: NSTA Press.

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Chapter 2

Konicek-Moran, R. 2008. Everyday science mysteries: Stories for inquiry-based science teaching. Arlington, VA: NSTA Press. Konicek-Moran, R. 2009. More everyday science mysteries: Stories for inquiry-based science teaching. Arlington, VA: NSTA Press. Padilla, M. 2006. President’s message. NSTA Reports 18 (9): 3.

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CHAPTER 3

USING THIS BOOK IN DIFFERENT WAYS

A

lthough the book was originally designed for use with K–8 students by teachers or adults in informal settings, it became obvious that a book containing stories and content material for teachers intent on teaching in an inquiry mode had other potential uses. I list a few of them below to show that the book has several uses beyond the typical elementary and middle school population in formal settings.

USING THE BOOK AS A CONTENT CURRICULUM GUIDE When asked by the University of Massachusetts to teach

in teacher education, I decided to use Everyday Science Mysteries as one of several texts to teach content material. A major premise in the book is that students, when engaged in answering their own questions, will delve into a topic at a level commensurate with their intellectual development and learning skills. Therefore, even though the stories were designed for people younger than themselves, the students in the class were able to find questions to answer that were at a level of sophistication that challenged them. During the fall 2007 semester this book was used as a text and curriculum guide for a class titled Exploring the Natural Sciences Through Inquiry at the University of Massachusetts in Amherst. The shortened version of the syllabus for the course follows:

a content course for a special master’s degree program

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Exploring the Natural Sciences Through Inquiry EDUC 692 O Fall 2007 Instructor: Dr. Richard D. Konicek, Professor Emeritus Course Description: This course is designed for elementary and middle school teachers who need, not only to deepen their content knowledge in the natural sciences, but also to understand how inquiry can be used in the elementary and middle school classroom. Natural sciences mean the Biological Sciences, Earth and Space Sciences and the Physical Sciences. Teachers will sample various topics from each of the above areas of science through inquiry techniques. The topics will be chosen from everyday phenomena such as Astronomy (Moon and Sun observations), Physics (motion, energy, thermodynamics, sound periodic motion), and Biology (botany, zoology, animal and plant behavior, evolution). Course Objectives: It is expected that each student will: • Gain content background in each of the three areas of natural science. • Be able to apply this content to their teaching methods. • Develop questions concerning a particular phenomenon in nature. • Design and carry out experiments to answer their questions. • Analyze experimental data and draw conclusions. • Consult various sources to verify the nature of their conclusions. • Read scientific literature appropriate to their studies. • Extend their knowledge to use with middle school children both in content and methodology. Relationship to the Conceptual Framework of the School of Education: Collaboration: Teachers will work in collaborative teams during class meetings to acquire science content and pedagogical knowledge and skills. Teachers will develop and implement formative Reflective Practice: assessment probes with their students. Multiple Ways of Knowing: Teachers will share science questions and their methods of inquiry chosen to answer those questions. Access, Equity, and Fairness: Teachers reflect on student understandings based on students’ stories. Teachers will explore formative assessment through Evidence-Based Practice: the use of probes. Required Texts: Hazen, R. M., and J. Trefil. 1991. Science matters. New York: Anchor Books. Keeley, P., F. Eberle, and J. Tugel. 2007. Uncovering student ideas in science: 25 more formative assessment probes, vol. 2. Arlington, VA: NSTA Press. Konicek-

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Moran, R. 2008. Everyday science mysteries. Arlington, VA: NSTA Press. Resource Texts: American Association for the Advancement of Science (AAAS). 2001. Atlas of science literacy (vol. 1). Washington, DC: Project 2061. American Association for the Advancement of Science (AAAS). 2007. Atlas of science literacy (vol. 2). Washington, DC: Project 2061. Driver, R., A. Squires, P. Rushworth, and V. Wood-Robinson. 1994. Making sense of secondary science. London: Routledge-Falmer. Keeley, P., F. Eberle, and L. Farrin. 2005. Uncovering student ideas in science, vol. 1. Arlington, VA: NSTA Press. Topics To Be Investigated in Volume One: Everyday Science Mysteries is organized around stories. The core concepts related to the National Science Education Standards developed by the National Research Council in 1996 are the basis for the concept selection. The story titles and related core concepts are shown in the matrices below.

Earth Systems Science Stories

Core Concepts States of Matter Change of State Physical Change Melting Systems Light Reflection Heat Energy Temperature Energy Water Cycle Rock Cycle Evaporation Condensation Weathering Erosion Deposition Rotation/Revolution Moon Phases Time

Moon Tricks

X X X

X X X

The Little Where Are the Master Frosty Tent That Acorns? Gardener Morning Cried X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X

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Chapter 3

Physical Sciences Stories

Core Concepts Energy Energy Transfer Conservation of Energy Forces Gravity Heat Kinetic Energy Potential Energy Position and Motion Sound Periodic Motion Waves Temperature Gas Laws Buoyancy Friction Experimental Design Work Change of State Time

Magic Bocce Grandfather’s Balloon Anyone? Clock X X X X X X X

X X X

X X

Neighborhood Telephone Service X X

How Cold Is Cold? X X X

X X X

X X X

X X X X X X

X X X X X

X

X X

X X

X

X

X

X

X X

X

Biological Sciences Core Concepts Animals Classification Life Processes Living Things Structure and Function Plants

About Me X X X

Bugs X X X X X

Stories Dried Seed Apples Bargains

Trees From Helicopters

X X X X

X X X

X X X X

X

X

X

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Adaptation Genetics/ Inheritance Variation Evaporation Energy Systems Cycles Reproduction Inheritance Change Genes Metamorphosis Life Cycles Continuity of Life

X X

X

X

X X

X

X X X X X X X X X

X

X

X

X X X X X

X X X X

X X X X X X

X

X

X X X

X X

X X

Chapter 3

X

X

X X

Assignments: Astronomy (25%): Everyone will be expected to explore the daytime astronomy sequence, which will aim to develop models of the Earth, Moon, and Sun relationships. Students will keep a Moon journal and Sun shadow journal over the course of the semester, which they will turn in periodically. Topics (50%): In addition, students will pick at least two topics from each of the Earth, Physical and Biological areas for study during the semester. Students will come up with a topic question and do an investigation or experiment regarding the topic questions posed. (For example: Are there acorns that do not need a dormancy period before germinating?) These questions and experiments will be shared with the class as they progress so that all students will either be directly involved in learning about the content or indirectly involved by listening to reports and critiquing those reports. In addition to the experiments, students will (1) involve their students in their experiments/investigations and (2) design and give formative assessment probes to their students to find out what knowledge they already possess. Students will be graded on their experimental designs, their presentations of their data and upon their conclusions. I will develop a rubric with the students that will address the goals stated above and their values to be calculated for their grades. Attendance/Participation (25%): Attendance at all course meetings is required. References for Course Development: American Association for the Advancement of Science (AAAS).1993. Benchmarks for science literacy. New York: Oxford University Press. Ausubel, D., J. Novak, and H. Hanensian. 1978. Educational psychology: A cognitive view. New York: Holt, Rinehart and Winston.

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Bransford, J. D., A. L. Brown, and R. R. Cocking, eds. 1999. How people learn. Washington, DC: National Academy Press. Duckworth, E. 1986. Inventing density. Grand Forks, ND: Center for Teaching and Learning, University of North Dakota. Driver, R., A. Squires, P. Rushworth, and V. Wood-Robinson. 1994. Making sense of secondary science: Research into children’s ideas. London and New York: Routledge Falmer. Hazen, R., and J. Trefil. 1991. Science matters: Achieving scientific literacy. New York: Anchor Books. Keeley, P. 2005. Science curriculum topic study: Bridging the gap between standards and practice. Thousand Oaks, CA: Corwin Press. Keeley, P., F. Eberle, and L. Farrin. 2005. Uncovering student ideas in science: 25 formative assessment probes, volume 1. Arlington, VA: NSTA Press. Keeley, P., F. Eberle, and J. Tugel. 2007. Uncovering student ideas in science: 25 more formative assessment probes, volume 2. Arlington, VA: NSTA Press. Konicek-Moran, R. 2008. Everyday science mysteries. Arlington, VA: NSTA Press. Martin, K., and E. Miller. 1990. Storytelling and science. In Toward a whole language classroom: Articles from language arts, ed. B. Kiefer, 1986–1989. Urbana, IL: National Council of Teachers of English. National Research Council (NRC). 2000. Inquiry and the national science education standards: A guide for teaching and learning. Washington, DC: National Academies Press. Osborne, R., and P. Fryberg. 1985. Learning in science: The implications of children’s science. Auckland, New Zealand: Heinemann. Schneps, M. A. 1996. A private universe project. Washington, DC: Harvard Smithsonian Center for Astrophysics. Shapiro, B. 1994. What children bring to light. New York: Teachers College Press. Watson, B., and R. Konicek. 1990. Teaching for conceptual change: Confronting children’s experience. Phi Delta Kappan May: 680–684.

The course was taught as a graduate course for teachers or prospective teachers of elementary or middle school students. The course could be classified as a content/pedagogy class for teachers who had minimal science backgrounds as well as minimal skills in teaching for inquiry. My premise was that if teachers would learn content through inquiry techniques, they would be convinced of their efficacy as learning techniques and would be likely to use them to teach content, in their own classes. As it turned out, those teacher-students who had classes of their own and were full-time teachers did work on their projects with their students with very satisfactory results according to the teachers. As a result, both teachers and students were learning science content through inquiry techniques. Because the teachers in the class were completing an assignment, they were able to be honest

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with their students about not knowing the outcome of their investigations. This is often a problem with teachers who are afraid to admit that they are learning along with the students. In this case the students were excited about learning along with their teachers and vice versa. Teachers with classrooms were also able to develop rubrics with their students for the grading of their explorations and therefore were involved with some metacognition as well. As a result of this small foray into the use of the book in this manner, I am convinced that the book can be used as a content guide for undergraduate and graduate content-oriented courses for teachers. As noted in the syllabus, the use of other supplementary texts for content and pedagogy add to the strength of the course in preparing teachers to use inquiry techniques and to learn content themselves. With the use of the internet, very little information is hidden from anyone with minimum computer skills. Unlike many survey courses chosen by teachers who are science-phobic, this course did not attempt to cover a great number of topics but to teach a few topics for understanding. The basic premise is that when deciding between coverage and understanding science topics and concepts, understanding wins every time. It is well known that our current curriculum in the United States has been faulted for being a mile wide and an inch deep. High-stakes testing seems to also add to the problem since almost all teachers whom I have interviewed over the last few years are reluctant to teach for understanding using inquiry methods because teaching for understanding takes more time and does not allow for coverage of the almost infinite amount of material that might appear on standardized tests. Thus, student misconceptions are seldom addressed and continue to persist even though students can do reasonably well on teacher-made tests and assessment tools and still hold onto their misconceptions. See Bonnie Shapiro’s book, What Children Bring to Light (1994).

USING THIS BOOK AS A RESOURCE BOOK FOR SCIENCE METHODS COURSES IN TEACHING PREPARATION PROGRAMS Traditionally, science methods courses in the United States are taught to classes

mainly composed of science-phobic students. One of the main goals of science methods courses is to make students comfortable with science teaching and to help students develop skills in teaching science to youngsters using a hands-on, minds-on approach. Unfortunately, a great many students come to these methods courses with a minimum of science content courses and many of those are either survey (non-laboratory) courses or courses taught in a large lecture format. In 12–13 weeks, methods instructors are expected to convert these students into confident, motivated teachers who are familiar with techniques that promote inquiry learning among their students. Having taught this type of course to

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Chapter 3

undergraduates and career-changing graduate students for over 30 years, I have found that making students comfortable with science is the first goal. This is often accomplished by assigning students science tasks that can be accomplished with a minimum of stress and with a maximum of success. Second, I try to instill the ideas commensurate with the nature of science as a discipline. Third, I find that it is often necessary to teach a little content for those who are rusty and need to clarify some of their own misconceptions. Lastly, but not least important, I try to acquaint them with resources in the field so that they know what is available to them as they enter their teaching careers. Obviously, here is an opportunity to acquaint them with current information about the learners themselves, how they learn, and how to teach for inquiry. As a final assignment for my methods classes, I assign the students the task of writing an everyday science mystery and a paper to accompany it, which will describe how they will use the story to teach a concept using the inquiry approach. The results have far exceeded what I had been receiving from the typical lesson plan used by others and me through the years. This book would not only provide the text on teaching science found in the early chapters but would provide a model for producing everyday science mysteries for topics of the students’ choices.

USING THE STORIES AS INTERACTIVE INQUIRY PLAYS Due to the innovation of the teachers of Knox County, Tennessee, and the actions

of instructional coaches Andrea Allen and Theresa Nixon, a new and exciting method of introducing the stories has been invented. These teachers have adapted the mystery stories into a theatrical mode called the “Everyday Science Mystery Readers Theater.” They invite teachers to make an interactive play out of the mystery stories instead of reading them. This involves the students in acting out the stories and in doing so, puts them further into the mysteries. We thank them for this innovation and invite you all to try this with your students. See Chapter 4: Science and Literacy for more information on student reading and writing in science. One of the plays, “Halloween Science,” is reproduced here with the teachers’ kind permission (see Chapter 15 for the original story and discussion).

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Everyday Science Mysteries Reader’s Theater “Halloween Science”

Chapter 3

Characters: Mom Dad Stella Narrator 1 Narrator 2

Setting: Farmer’s Market Narrator 1: Stella and her parents went out to the farmer’s market on a chilly October day to look for a pumpkin to make into a jack-o-lantern. They had several goals in mind. Narrator 2: One was to find the best looking pumpkin to carve for decoration on Halloween. The second was to find a pumpkin that would have the most seeds so they could make salted pumpkin seeds for snack. Narrator 1: Stella and her family loved to eat pumpkin seeds and had a great recipe for making them. Narrator 2: When they got to the market, pumpkins of all sizes and shapes surrounded them and the sight was overwhelming. Narrator 1: How in the world would they find the perfect pumpkin? And how would they know which one had the most seeds? Stella: I think the biggest pumpkin will have the most seeds. It makes perfect sense that the bigger the pumpkin, the more seeds it will have. Dad: Look at the number of creases on the pumpkin and that will tell you which one has more seeds. Mom: Well, I think the heaviest one will have the most seeds. Because the heavier the pumpkin the more stuff is inside. Stella: But Mom, the heaviest will be the biggest, won’t it? And all that stuff inside isn’t just seeds is it? Dad: Maybe not. Let’s lift up a few big and smaller ones and see. And as for the gunk inside, we’ll have to see what it’s used for. Maybe we can figure that out when we open it up.

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Narrator 1: They ended up buying several pumpkins and taking them home to find out the answers to their questions. It turned out that when they began to work on the pumpkins, they had a lot more questions than they did at the market.

USE FOR HOMESCHOOL PROGRAMS Homeschooling parents have a great many resources at their disposal, as any inter-

net search will show. Curricular suggestions and materials are available for those parents and children who choose to conduct their education at home. Science is one of those subjects that might be difficult for many parents whose science backgrounds are a bit weak or outdated. Parents and children working together to solve a story-driven mystery could use this book easily. The connections to the national Standards and the Benchmarks in science also help in making sure that the home schooling curriculum is uncovering the nationally approved scientific concepts. Parents would use the book just as any teacher would use it except there would be fewer opportunities for class discussions and the parents would have to do a bit more discussion with their children to solidify their understanding of their investigations.

REFERENCE Shapiro, B. 1994. What children bring to light. New York: Teachers College Press.

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Chapter 4

Science and Literacy

W

hile heading into the final chapter before launching into the stories, I couldn’t resist introducting you to a piece of literature that is seldom read except by English majors. The quotation that follows is from Irish novelist James Joyce in his classic book Ulysses, written in 1922: Where was the chap I saw in that picture somewhere? Ah yes, in the dead sea, floating on his back, reading a book with a parasol open. Couldn’t sink if you tried: so thick with salt. Because the weight of the water, no, the weight of the body in the water is equal to the weight of the what? Or is it the volume is equal to the weight? It’s a law something like that. Vance in High school cracking his fingerjoints, teaching. The college curriculum. Cracking curriculum. What is weight really when you say the weight? Thirtytwo feet per second, per second. Law of falling bodies: per second, per second. They all fall to the ground. The earth. It’s the force of gravity of the earth is the weight. (p. 73) In the novel, Joyce’s main character Bloom recalls a picture of someone floating in the Dead Sea, and tries to recall the science behind it. Have you or have you observed others who, while trying to recall something scientific, resorted to a mishmash of scientic knowledge,

half-remembered and garbled? (For this foray into literature, I am indebted to Michael J. Reiss who called my attention to this passage in an article of his in School Science Review.) In his school days, Bloom seems to have been fascinated both with the curriculum and the teacher in his physics class. However, Bloom’s memory of the science behind buoyancy runs the gamut from unrelated science language pouring out of his memory bank to visions of his teacher cracking his finger joints. Unfortunately, even today, this might well be the norm rather than the exception. This phenomenon is exactly what we are trying to avoid in our modern pedagogy and now leads us to the main point of this chapter. There are many ways of connecting literacy and science. We shall look briefly at the research literature and find some ideas that will make the combination of literacy and science not only worthwhile but also essential for learning.

LITERACY AND SCIENCE

In pedagogical terms there are differences between scientific literacy and the curricular combination of science and literacy, but perhaps they have more in common than one might expect. Scientific literacy is the ability to

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understand scientific concepts so that they have a personal meaning in everyday life. In other words, a scientifically literate population can use their knowledge of scientific principles in situations other than those in which they learned them. For example, I would consider people scientifically literate if they were able to use their understanding of ecosystems and ecology to make informed decisions about saving wetlands in their community. This is of course, what we would hope for in every aspect of our educational goals regardless of the subject matter. Literacy refers to the ability to read, write, speak, and make sense of text. Since most schools emphasize reading, writing, and mathematics, they often take priority over all other subjects in the school curriculum. How often have I heard teachers say that their major responsibility is reading and math, and that there is no time for science? But there is no need for competition for the school day. I believe that this misconception is caused by the lack of understanding of the synergy created by integration of subjects. In synergy, you get a combination of skills that surpasses the sum of the individual parts. So what does all of this have to do with teaching science as inquiry? There is currently a strong effort to combine science and literacy. One reason is that there is a growing body of research that stresses the importance of language in learning science. “Hands-on” science is nothing without its “minds-on” counterpart. I am fond of reminding audiences that a food fight is a hands-on activity, but one does not learn much through mere participation, except perhaps the finer points of the aerodynamic properties of Jell-O. The understanding of scientific principles is not imbedded in the materials themselves or in the manipulation of these materials. Discussion, argumentation, discourse of all kinds, group consensus and social interaction—all forms of communication are necessary for students to make meaning out of the activities in which they have engaged. And these require language in the form of writing, reading, and particularly speaking. They require that students think about their thinking—that they hear their own and others’ thoughts and ideas spoken out loud and perhaps eventually see them in writing to make sense of what they have been doing and the results they have been getting in their activities. This is the often forgotten “minds-on” part of the “hands-on, minds-on” couplet. Consider the following: In schools, talk is sometimes valued and sometimes avoided, but—and this is surprising—talk is rarely taught. It is rare to hear teachers discuss their efforts to teach students to talk well. Yet talk, like reading and writing, is a major motor—I could even say the major motor—of intellectual development. (Calkins 2000, p. 226) For a detailed and very useful discussion of talk in the science classroom, I refer you to Jeffrey Winokur and Karen Worth’s chapter, “Talk in the Science Classroom: Looking at What Students and Teachers Need to Know and Be Able to Do” in Linking Science and Literacy in the K–8 Classroom (2006). Also check out Chapter 8 in this book. There is also recent evidence that ELL learners gain a great deal from talking, in both their science learning and new language acquisition (Rosebery and Warren 2008).

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Linking inquiry-based science and literacy has strong research support. First, the conceptual and theoretical work of Padilla and his colleagues suggest that inquiry science and reading share a set of intellectual processes (e.g., observing, classifying, inferring, predicting, and communicating) and that these processes are used whether the student is conducting scientific experiments or reading text (Padilla, Muth, and Padilla 1991). Helping children become aware of their thinking as they read and investigate with materials will help them understand and practice more metacognition. You, the teacher, may have to model this for them by thinking out loud yourself as you view a phenomenon. Help them to understand why you spoke as you did and why it is important to think about your process of thinking. You may say something like, “I think that warm weather affects how fast seeds germinate. I think that I should design an experiment to see if I am right.” Then later, “Did you notice how I made a prediction that I could test in an experiment?” Modeling your thinking can help your students see how and why the talk of science is used in certain situations. Science is about words and their meanings. Postman made a very interesting statement about words and science. He said “Biology is not plants and animals. It is language about plants and animals…. Astronomy is not planets and stars. It is a way of talking about planets and stars” (1979, p.165). To emphasize this point even further, I might add that science is a language, a language that specializes in talking about the world and being in that world we call science. It has a special vocabulary and organization. Scientists use this vocabulary and organization when they talk about their work. Often, it is called “discourse” (Gee 2004). Children need to learn this discourse when they present their evidence, when they argue the fine points of their work, evaluate their own and others’ work and refine their ideas for further study. Students do not come to you with this language in full bloom; in fact the seeds may not even have germinated. They attain it by doing science and being helped by knowledgeable adults who teach them about controlling variables, conducting fair tests, having evidence to back up their statements, and using the processes of science in their attempts at what has been called “firsthand inquiry” (Palincsar and Magnusson 2001). This is inquiry that uses direct involvement with materials, or in other more familiar words, the hands-on part of scientific investigation. The term secondhand investigations refers to the use of textual matter, lectures, reading data, charts, graphs, or other types of instruction that do not feature direct contact with materials. Cervetti et al. (2006) put it so well: [W]e view firsthand investigations as the glue that binds together all of the linguistic activity around inquiry. The mantra we have developed for ourselves in helping students acquire conceptual knowledge and the discourse in which that knowledge is expressed (including particular vocabulary) is “read it, write it, talk it, do it!”—and in no particular order, or better yet, in every possible order. (p. 238)

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Chapter 4

So you can see that it is also important that the students talk about their work; write about their work; read about what others have to say about the work they are doing, in books or via visual media; and take all possible opportunities to document their work in a way that is useful to them in looking back at what they have found out about their work.

THE LANGUAGE OF SCIENCE Of course, writing, talking, and reading in the discipline of science is different

than other disciplines. For example, science writing is simple and focuses on the evidence obtained to form a conclusion. But science includes things other than just verbal language. It includes tactile, graphic, and visual means of designing studies, carrying them out, and communicating the results to others. Also important is that science has many unfamiliar words; many common words such as work, force, plant food, compound, and density have different meanings in the real world of the student but have precise and often counterintuitive meanings in science. For example, if you push against a car for 30 minutes until perspiration runs off your face, you feel as though you have “worked” hard even though the car has not budged a centimeter. In physics, unless the car has moved, you have done no work at all. We tell students that plants make their own food and then show them a bag of “plant food.” We tell children to “put on warm clothes,” yet the clothes have nothing to do with producing warmth. Students have to change their way of communicating when they study science. They must learn new terminology and clarify old terms in scientific ways. We as teachers can help in this process by realizing that we are not just science teachers but also language teachers. When we talk of scientific things, we talk about them in the way the discipline works. We should not avoid scientific terminology but try to connect it whenever possible to common metaphors and language. We should use pictures and stories. We need also to know that science contains many words that ask for thought and action on the part or the students. Sentences with words like compare, evaluate, infer, observe, modify, and hypothesize prompt students to solve problems. We can only teach good science by realizing that language and intellectual development go hand in hand and that one without the other is mostly meaningless.

SCIENCE NOTEBOOKS Many science educators have lately touted science notebooks as an aid to stu-

dents involving themselves more in the discourse of science (Campbell and Fulton 2003). Their use has also shown promise in helping English language learners (ELLs) in the development of language skills as well as learning science concepts and the nature of science.

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Science notebooks differ from science journals and science logs in that they are not merely for recording data (logs) or reflections of learning (journals), but are meant to be used continuously for recording experimentation, designs, plans, thinking, vocabulary, and concerns or puzzlement. The science notebook is the recording of past, and present thoughts and predictions and are unique to each student. The teacher makes sure that the students have ample time to record events and to also ask for specific responses to such questions as, “What still puzzles you about this activity?” For specific ideas for using science notebooks and for information on the value of using the notebooks in science, see Science Notebooks: Writing About Inquiry by Brian Campbell and Lori Fulton (2003). You can assume that science notebooks are a given in what I envision as an inquiry-oriented classroom. While working in an elementary school years ago, I witnessed some minor miracles of children writing to learn. The most vital lesson for us as teachers was the importance of asking children to write each day about something that still confused them. The results were remarkable. As we read their notebooks, we witnessed their metacognition, and their solutions through their thinking “out loud” in their writing. The use of science notebooks should be an opportunity for the students to record their mental journey through their activity. Using the stories in this book, the science notebook would include the specific question that the student is concerned with, the lists of ideas and statements generated by the class after the story is read, pictures or graphs of data collected by the student and class, and perhaps the final conclusions reached by the student or class as they try to solve the mystery presented by the story. Let us imagine that your class has reached a conclusion to the story they have been using and have reached consensus on that conclusion. What options are open to you as a teacher for asking the students to finalize their work? At this juncture, it may be acceptable to have the students actually write the “ending” to the story or write up the conclusions in a standard lab report format. The former method, of course, is another way of actually connecting literacy and science. Many teachers prefer to have their students at least learn to write the “boiler plate” lab reports, just to be familiar with that method, while others are comfortable with having their students write more anecdotal kinds of reports. My experience is that when students write their conclusions in an anecdotal form, while referring to their data to support their conclusions, I am more assured that they have really understood the concepts they have been chasing rather than filling in the blanks in a form. In the end, it is up to you, the classroom teacher, to decide. Of course, it could be done both ways. As mentioned earlier, a major factor in designing these stories and follow-up activities is based upon one of the major tenets of a philosophy called constructivism. That tenet is that knowledge is constructed by individuals in order to make sense of the world in which they live. If we believe this, then the knowledge that each individual brings to any situation or problem must be factored into the way that person tries to solve that problem. By the same token, it is most important to realize that the

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Chapter 4

identification of the problem and the way the problem is viewed are also factors determined by each individual. Therefore it is vital that the adult facilitator encourage the students to bring into the open, orally and in writing, those ideas they already have about the situation being discussed. In bringing these preconceptions out of hiding, so to speak, all of the children and the teacher can begin playing with all of the cards exposed and alternative ideas about topics can be addressed. Data can be then analyzed openly without any hidden agendas in childrens’ minds to sabotage learning. You can find more about this process in the series Uncovering Student Ideas in Science: 25 Formative Assessment Probes, vols.1–4 (2005, 2007, 2008, 2009). The stories also point out that science is a social, cultural, and therefore human enterprise. The characters in our stories usually enlist others in their investigations, their discussions, and their questions. These people have opinions and hypotheses and are consulted, involved, or drawn into an active dialectic. Group work is encouraged, which in a classroom would suggest cooperative learning. At home, siblings and parents may become involved in the activities and engage in the dialectic as a family group. The stories can also be read to the children. In this way children can gain more from the literature than if they had to read the stories by themselves. A child’s listening vocabulary is usually greater than his or her reading vocabulary. Words that are somewhat unfamiliar to them can be deduced by the context in which they are found. Or, new vocabulary words can be explained as the story is read. We have found that children are always ready to discuss the stories as they are read and therefore become more involved as they take part in the reading. So much the better because getting involved is what this book is all about; getting involved in situations that beg for problem finding, problem solving, and construction of new ideas about science in everyday life.

HELPING YOUR STUDENTS DURING INQUIRY How much help should you give to your students as they work through the prob-

lem? A good rule of thumb is that you can help them as much as you think necessary as long as the children are still finding the situation problematic. In other words, the children should not be following your lead but their own lead. If some of these leads end up in dead ends, then that aspect of scientific investigation is part of their experience too. Science is full of experiences which are not productive. If children read popular accounts of scientific discovery, they could get the impression that the scientist gets up in the morning, says, “What will I discover today?” and then sets off on a clear, straight path to an elegant conclusion before suppertime rolls around. Nothing could be further from the truth! But it is very important to note that a steady diet of frustration can dampen students’ enthusiasm for science. Dead ends can be viewed as signaling a need to develop a new plan or ask the question in a different way. Most important, dead ends should not be looked upon as failures. They are more like opportunities to try again in a different way with a

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clean slate. The adult’s role is to keep a balance so that motivation is maintained and interest continues to flourish. Sometimes this is more easily accomplished when kids work in groups. Most often nowadays, scientists work in teams and use each other’s expertise in a group process, Many people do not understand that the scientific process includes luck, personal idiosyncrasies, and feelings, as well as the so-called scientific method. The term scientific method itself sounds like a recipe guaranteed to produce success. The most important aid you can provide for your students is to help them maintain their confidence in their ability to do problem solving using all of their ways of knowing. They can use metaphors, visualizations, drawings, or any other method with which they are comfortable to develop new insights into the problem. Then they can set up their study in a way that reflects the scientific paradigm including a simple question, controlling variables, and isolating the one variable they are testing. Next, you can help them to keep their experimental designs simple and carefully controlled. Third, you can help them to learn keep good data records in their science notebooks. Most students don’t readily see the need for this last point, even after they have been told. They don’t see the need because the neophyte experimenter has not had much experience with collecting usable data. Until they realize that unreadable data or necessary data not recorded can cause a problem, they see little use for them. The problem is that they don’t see it as a problem. Children don’t see the need for keeping good shadow length records because they are not always sure what they are going to do with them in a week or a month from now. If they are helped to see the reasons for collecting data and that these data are going to be evidence of a change over time, then they will see the purpose of being able to go back and revisit the past in order to compare it to the present. In this way they can also see the reasons for keeping a log in the first place. In experiences we have had with children, forcing them to use prescribed data collection worksheets has not helped them to understand the reasons for data collection at all and in some cases has actually caused more confusion or amounted to little more than busy work. On one occasion while circulating around a classroom where children were engaged in a worksheet-directed activity, an observer asked a student what she was doing. The student replied without hesitation, “step 3.” Our goal is to empower students engaged in inquiry to the point where they are involved in the activity at a level where all of the steps, including step 3, are designed by the students themselves and for good reason—to answer their own questions in a logical, sequential, meaningful manner. We believe it can be done, but it requires patience on the part of the adult facilitators and faith that the children have the skills to carry out such mental gymnastics, with a little help from their friends and mentors. One last word about data collection. After spending years being a scientist and working with scientists, one common element stands out for me. Scientists keep on their person a notebook that is used numerous times during the day to record interesting items. The researcher may come across some interesting data

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Chapter 4

that may not seem directly connected to the study at the time but he or she makes some notes about it anyway because that entry may come in handy in the future. Memory is viewed as an ephemeral thing, not to be trusted. Scientists’ notebooks are a treasured and essential part of the scientific enterprise. In some cases they have been considered legal documents and used as such in courts of law. There is an ethical expectation that scientists record their data honestly. Many times, working with my mentor, biologist Skip Snow in the Everglades National Park Python Project, I have seen Skip refer to previous entries when confronted with data that he thinks may provide a clue to a new line of investigation. Researchers don’t leave home without notebooks.

WORKING WITH ENGLISH LANGUAGE LEARNER (ELL) POPULATIONS Now, suppose that members of your class are from other cultures and have a lim-

ited knowledge of the English language. Of what use is inquiry science with such a population and how can you use the discipline to increase both their language learning and their science skills and knowledge? First of all, let’s take a look at the problems associated with learning with the handicap of limited language understanding. Lee (2005) in her summary of research on ELL students and science learning, points to the fact that students who are not from the dominant culture are not aware of the rules and norms of that culture. Some may come from cultures in which questioning (especially of elders) is not encouraged and where inquiry is not supported. Obviously, to help these children cross over from the culture of home to the culture of school, the rules and norms of the new culture must be explained carefully and visibly, and the students must be helped to take responsibility for their own learning. You can find specific help in a recent NSTA publication by Ann Fathman and David Crowther (2006) entitled Science for English Language Learners: K–12 Classroom Strategies. Also very helpful is another NSTA publication, Linking Science and Literacy in the K–8 Classroom. Chapter 12, “English Language Development and the ScienceLiteracy Connection”(Douglas and Worth 2006). Add to this array of written help two more books: Teaching Science to English Language Learners: Building on Students’ Strengths (Rosebery and Warren 2008) and Science for English Language Learners: K–12 Classroom Strategies (Fathman and Crowther 2006). Finally, an article from Science and Children (Buck 2000) entitled “Teaching Science to English-as-Second Language Learners” has many useful suggestions for working with ELL students. I can summarize as best as I can a few ideas and will also put them into the teacher background sections when appropriate. Experts agree that vocabulary building is very important for ELL students. You can focus on helping these students identify objects they will be working with

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in their native language and in English. These words can be entered in science notebooks. Some teachers have been successful in using a teaching device called a “working word wall.” This is an ongoing poster with graphics and words that are added to the poster as the unit progresses. When possible, real items or pictures are taped to the poster. This is visible for constant review and kept in a prominent location, since it is helpful for all students, not just the ELL students. Many teachers suggest that the group work afforded by inquiry teaching helps ELL students understand the process and the content. Pairing ELL students with English speakers will facilitate learning since often students are more comfortable receiving help from peers than from the teacher. They are more likely to ask questions of peers as well. It is also likely that explanations from fellow students may be more helpful, since they’ll probably explain things in language more suitable to those of their own age and development. Use the chalkboard or whiteboard more often. Connect visuals with vocabulary words. Remember that science depends upon the language of discourse. You might also consider inviting parents into the classroom so that they can witness what you are doing to help their children to learn English and science. Spend more time focusing on the process of inquiry so that the ELL students will begin to understand how they can take control over their own learning and problem solving. The SIOP model (Echevarria, Vogt, and Short 2000) has been earning popularity lately with teachers who are finding success in teaching science to ELL students. SIOP is an acronym for Sheltered Instruction Observation Protocol. It emphasizes hands-on/minds-on types of science activities that require ELL students to interact with their peers using academic English. You can reach the SIOP Institute website at www.siopinstitute.net. While it is difficult to summarize the model succintly, the focus is on melding the use of academic language with inquiry-based instruction. Every opportunity to combine activity and inquiry should be taken and all of the many types of using language be stressed. This would include writing, speaking, listening, and reading. There is also a strong emphasis on ELL students being paired with competent English language speakers so that they can listen and practice using the vocabulary with those students who have a better command of the language. In short, the difference between most other ESL programs and Sheltered Instruction is that in the latter, the emphasis is on connecting the content area learning and language learning in such a way that they enhance each other rather than focusing on either the content or the language learning as separate entities. In many programs it is assumed that ELL students cannot master the content of the various subjects because of their lack of language proficency. Sheltered Instruction assumes that given more opportunities to speak, write, read, talk and listen in the context of any subject’s language base, ELL students can master the content as well as the academic language that goes with the content. Teachers also need to be more linguistically present during classroom management tasks. They need to talk with students to make sure they are interpreting their inquiry tasks and learning how to explain their observations and conclusions

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Chapter 4

in their new language. The teacher’s role includes making sure students are focused by reminding them to write things down and to help them discuss their findings in English. As I said before, it is not only the ELL students who need to work on their academic language but all students who need to learn that science has a way of using language and syntax that is different than other disciplines. All students can benefit from being considered Science Language Learners. And now, on to the stories which I hope will inspire your students to become active inquirers and enjoy science as an everyday activity in their lives.

REFERENCES Buck, G. A. 2000. Teaching science to English-as-second language learners. Science and Children 38 (3): 38–41. Calkins, L. M. 2000. The art of teching reading. Boston: Allyn and Bacon. Campbell, B., and L. Fulton. 2003. Science notebooks: Writing about inquiry. Portsmouth, NH: Heinemann. Cervetti, G. N., P. D. Pearson, M. Bravo, and J. Barber. 2006. Reading and writing in the service of inquiry-based science. In Linking Science and Literacy in the K–8 classroom, ed. R. Douglas and K. Worth, 221–244. Arlington, VA: NSTA Press. Douglas, R., and K. Worth, eds. 2006. Linking science and literacy in the K–8 classroom. Arlington, VA: NSTA Press. Echevarria, J., M. E. Vogt, and D. Short. 2000. Making content comprehensible for English language learners: The SIOP model. Needham Heights. MA: Allyn and Bacon. Fathman, A., and D. Crowther. 2006. Science for English language learners: K–12 classroom strategies. Arlington, VA: NSTA Press. Gee, J. P. 2004. Language in the science classroom: Academic social languages as the heart of school-based literacy. In Crossing borders in literacy and science instruction: Perspectives on theory and practice, ed. E. W. Saul, 13–32. Newark, International Reading Association. Joyce, J. 1922. Ulysses. Repr., New York: Vintage, 1990. Page reference is to the 1990 edition. Keeley, P., F. Eberle, and C. Dorsey. 2008. Uncovering student ideas in science, volume 3: Another 25 formative assessment probes. Arlington, VA: NSTA Press. Keeley, P., F. Eberle, and L. Farrin. 2005. Uncovering student ideas in science, volume 1: 25 formative assessment probes. Arlington, VA: NSTA Press. Keeley, P., F. Eberle, and J. Tugel. 2007. Uncovering student ideas in science, volume 2: 25 more formative assessment probes. Arlington, VA: NSTA Press. Keeley, P., and J. Tugel. 2009. Uncovering student ideas in science, volume 4: 25 new formative assessment probes. Arlington, VA: NSTA Press. Lee, O. 2005. Science education and student diversity: Summary of synthesis and research agenda. Journal of Education for Students Placed At Risk 10 (4): 431–440.

36 N at io nal Science Teachers Asso ciatio n Copyright © 2013 NSTA. All rights reserved. For more information, go to www.nsta.org/permissions.

Padilla M. J., K. D. Muth, and R. K. Padilla. 1991. Science and reading: Many process skills in common? In Science learning: Processes and applications, eds. C. M. Santa and D. E. Alvermann, 14–19. Newark, DE: International Reading Association. Palincsar, A. S., and S. J. Magnusson. 2001. The interplay of firsthand and textbased investigations to model and support the development of scientific knowledge and reasoning. In Cognition and instruction: Twenty-five years of progress, eds. S. Carver and D. Klahr, 151–194. Mahwah, NJ: Lawrence Erlbaum. Postman, N. 1979. Teaching as a conserving activity. New York: Delacorte. Reiss, M. J. 2002. Reforming school science education in the light of pupil views and the boundaries of science. School Science Review 84 (307). Rosebery, A. S., and B. Warren, Eds. 2008. Teaching science to English language learners: Building on students’ strengths. Arlington, VA: NSTA Press. Winokur, J., and K. Worth. 2006. Talk in the science classroom: Looking at what students and teachers need to know and be able to do. In Linking science and literacy in the K–8 classroom, ed. R. Douglas and K. Worth, 43–58. Arlington, VA: NSTA Press.

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Chapter 4

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The Stories and BaCKground Material for Teachers

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Everyday Life SciencE Mysteries Matrix Stories Basic Concepts Animals

About Me

Oatmeal Bugs

X

X

Classification

Dried Apples

Seed Bargains

Trees From Helicopters

X

X

X

X

Life Processes

X

X

X

X

X

Living Things

X

X

X

X

X

X

X

Structure and Function Plants

X

Adaptation

X X

X

X X

Genetics

X

X

X

X

Variation

X

X

X

X

X

X

Evaporation

X

Energy

X

X

Systems

X

X

X

Cycles

X

X

X

X

X

Reproduction

X

X

X

X

X

Inheritance

X

X

X

Change of State

X

Genes

X

X

X

X X

X X

Metamorphosis

X

Life Cycles

X

X

Continuity of Life

X

X

X

X

X

Basic Concepts

Worms Are for More Than Bait

What Did That Owl Eat?

Trees From Helicopters, (Cont)

Flowers: More Than Just Pretty

A Tasteful Story

X

X

Life Cycles

X

Classification of Organisms

X

Animal Behavior

X

Adaptation

X

X

Ecology

X

X

Diversity of Life

X

X

Structure and Function

X

X

X X

Cells Organs

X

Functions of Living Things

X

Senses

X

X

X

X

X

X

X

X

X

X

X

X

X

X

Interdependency of Living Things

X

X

Needs of Organisms

X

X

Flow of Energy

X

X

Transformation of Matter

X

X

X X

continued

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The Trouble With Bubble Gum

Basic Concepts

Plunk, Plunk

Life Cycles

X

Classification of Organisms

X

In a Heartbeat

Animal Behavior

Hitchhikers

Halloween Science

X

X

X

X

X

Adaptation

X

Ecology Diversity of Life

X

Structure and Function

X

Functions of Living Things

X

Health

X

Experimental Design

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X X

X

Needs of Organisms

X

Transformation of Matter

X

X

X

X

Continuity of Life

X

X

Plants

X

Nutrition

X X

X X

X

Interdependency of Living Things

Methods of Inquiry

X X

X

Cycles

X

Variation

X

X

X X

X

X

X

X

Looking at Lichens

Baking Bread

Fungi

X

X

Algae

X

Symbiosis

X

Spores

X

X

Reproduction

X

X

X

X

Life Cycles

X

X

X

X

Basic Concepts

Yeast

Springtime in the Greenhouse

X X

Reaction Time

Seedlings in a Jar

X

Metabolism

X

X

X

X

Chemical Change

X

X

X

X

Physical Change

X

X

X

X

Nutrition

X

X

X

X

X

X

X

X

Germination Photosynthesis

X

Nervous System

X

Reaction Time

X

Stimuli

X

Responses

X

Averages Systems

X

X

X

Open Systems

X

X

X

X

Closed Systems

X X

Atmosphere

X

X

X

Experimental Design

X

X

X

X X

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X

Chapter 5

Trees From Helicopters

H

elicopters! That’s what they looked like. She had seen them before but this spring, Sarah was completely fascinated by the little spinning objects falling out of the sky and landing on the porch. There were many hundreds of them. She and her brother had been given the task of sweeping them off the porch. “Not on the ground. Not in the garden. We don’t want a bunch of trees growing in our flower beds.”

Sarah’s older brother Eric, who had received them from their mother, gave these warnings. “What kind of trees do they grow up to be?” asked Sarah. “Well, they fall out of maple trees so they must become mighty oaks, I guess,” teased Eric. “Come on Eric, how do you know they fall out of maple trees?” asked Sarah. “Well, my first clue was seeing them there on the

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maple trees,” said Eric pointing up to the overhanging branches of the red maple. “I guess I never noticed them on the trees.” As she watched, a small breeze rippled through the tree and several of the little flyers began to swirl to the ground, spinning merrily all the way down looking like little helicopters. “Do all trees make these?” asked Sarah. “Of course not! Oak trees make acorns and uh, other trees make, uh, their own kind, I guess,” stumbled Eric. He wasn’t sure about this fact but had to keep his big brother know-it-all image. “Funny, I never thought about trees making seeds,” Sarah thought to herself, being careful what she said out loud to her brother. “I wonder if trees have flowers, too.” “Could I grow a maple tree on purpose—you know, like in a pot?” asked Sarah. “Or, an acorn?” “Nah,” Eric said. “I seem to remember my biology teacher saying that some seeds need to get frozen or cold or something before they could sprout. Acorns especially I think, or some acorns—I don’t remember exactly.” They continued sweeping and the conversation stopped. “What other seeds grow on trees?” asked Sarah later when her mother was tucking her in at bedtime. “What?” answered her mother, completely puzzled. “Eric and I were talking about growing tree seeds, you know, maple helicopters, acorns in pots. And I was wondering what other seeds grow on trees.” “Well, do you want to count apple and orange seeds as growing on trees?” asked Mother. Sarah stopped and thought before she spoke. “Yeah, I guess so but I never thought much about apple and orange seeds as seeds except for spitting them out.” She thought some more. Then she blurted out, “Do they need to be frozen too?” “Frozen?” mother responded, confused. “Eric said that his teacher said that some seeds need to be frozen before they can become trees.” “That’s a new one on me,” said Mother, “We could look it up, I guess. But for now, it’s time to get to sleep. We’ll talk more about it tomorrow. Good night.” And she planted a kiss on Sarah’s forehead and turned out the light. “Good night, mom,” and she closed her eyes. But the visions of all those trees growing in pots on her windowsill stayed with her until she went to sleep.

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Purpose This story is aimed at promoting not only inquiry into the germination of tree seeds but seeing trees as typical flowering plants, also known as angiosperms. There is also ample opportunity to take an excursion into fruits and seeds and the germination of seeds.

Related Concepts • Plant life • • • •

Adaptation Reproduction Structure and function Life processes

• • • •

Living things Germination Life cycles Characteristics of life

Don’t Be Surprised The main misconception might well be that the things we call seeds are really

fruits. The story characters talk about the maple seeds and acorn seeds to show that children and adults are not aware of the fruits that enclose the seeds. Maple “helicopters” (schizocarps) are fruits, as are acorns (nuts). The seeds lie within and are protected by the fruits. Try asking a question such as, “What is the purpose of the fleshy material around the seeds in a fruit?” Most likely you will receive the answer that the purpose of the flesh of an apple or orange or other fruits is to provide nutrition for the seeds, rather than to entice animals to eat the fruit and distribute the seeds. Children and adults alike are also surprised by the thought of trees having flowers and producing fruits and seeds. Somehow, they don’t think of acorns as fruits but more as squirrel food. Maple fruits are merely trouble-causing objects that fall from the trees and have to be swept up each spring. And other than ornamentals, have you thought of trees as having the flowers that are a prerequisite for producing fruits and seeds? Have you ever noticed an oak flower or a willow flower? Have you noticed a willow seed or a poplar seed? If you live in a temperate climate, you probably have and never realized what they were. Children and adults seldom think of trees producing fruits other than those they eat and children may find it difficult to depart from the supermarket definition of a fruit. Therefore the fruits of trees and those of shrubs such as milkweed, Russian olive, roses, and sumac are not thought of as such.

Content Background Seeds are the plants’ “babies” ready to produce the next generation. Seeds are

usually in a state of dormancy and when this dormancy is broken and the new

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Chapter 5

plant breaks the seed coat and exits the seed, that process is called germination. The group of plants called angiosperms is defined by the fact that their seeds are enclosed in a mature, enlarged ovary of the flower that produced them, a fruit. That fruit is often tasty and enticing to animals that eat them and the seeds are dispersed so that they can grow into successful plants. Contrast these with the gymnosperms in which the seeds are “naked” and not enclosed in an ovary, thus have no fruits. These are the conifers such as pines, cedars, and most evergreens. Their seeds are found, lying on the scales of the cone. These are, however, tasty enough to entice squirrels and chipmunks to rip into the cones and while eating some, spread others. Experts disagree on whether these need to be cooled so you and your students will be working on the edge of research. Isn’t that exciting? You can try both ways and see what you can find out—a true inquiry-based study. Acorns can come from many types of oaks; white oak, red oak, pin oak, and other species. Maples are also varied and include the red maple, sugar maple, Norway maple, swamp maple, and so on. However, the fruits and seeds of each genus are similar. The white oak produces one of few acorns that do not require cold temperatures for germination and its acorns germinate during the autumn of their maturity. The other species require temperatures of at least 0–2° C for a minimum of six weeks before they can be expected to germinate. During this time they become dormant. (Some dormant seeds can remain so for centuries and one seed was reported to be viable after a thousand years in a desert-like climate). Therefore, in the natural world, acorns that require dormancy do not germinate until the spring of the following year at the earliest. Just as we can force bulbs, we can force acorns by placing them in damp peat moss or soil, in a plastic bag or container, and placing them outdoors, in cool climates, or in a refrigerator, which is set at the required temperature. The bag must be left open to allow transfer of gases. Maple seeds do not require cooling and can be planted immediately. Your students will probably be familiar with acorns and maple seeds if they live in temperate climates. Even in subtropical areas, the swamp maple, the live oak, and swamp oak are present. Since maples and oaks are two of the most common trees in the continental United States, teachers should have little trouble obtaining these seeds. If they are not available, the seeds of any common tree will satisfy the needs of a class wishing to engage in inquiry about trees and their seeds. In certain climates some tree flowers are very obvious and flamboyant. In others they are hardly noticeable. But if seeds are encased in a fruit, there must have been flowers. These types of plants are called angiosperms. These plants have their seeds encased in the ovary of the flower and the ovary usually becomes fleshy as in an apple or cherry. Acorns by this definition are also fruits (actually classified as single-seeded nuts), and are so common that they are often overlooked as objects of study. The same can be said for the maple fruits. I would like to suggest that you read a most enjoyable book on botany, which will broaden your background on this topic. The book is The Botany of Desire by Michael Pollan (2001).

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A fruit is the ripened ovary of the seed plant and its contents. Thus you can see that this is a botanical definition, not a supermarket definition. Fruits range from what we normally call vegetables to fruits like apples and oranges, berries, tomatoes, cherries, and of course, maple and oak fruits, coco plums, and pond apples. The fruit protects the seeds within it and provides the mechanism for distributing the seeds. You may well ask of each fruit you see, “How do you help the seeds you enclose, get to where they can best germinate and produce new plants? Are you tasty, so that you attract animals that eat you or bury you and thus spread your seeds far from the original tree? Do you pop open and propel your seeds or do you produce little parachutes so that they can fly in the wind? Are you shaped like tiny helicopters so that the wind can carry you? Do you have a hard protective case so that you protect your seeds from inclement weather? Do you have a Velcrolike surface on you so that you stick to animals’ fur or feathers and travel great distances from your mother plant?” Through natural selection, or paraphrased, survival of the fittest, over the eons that plants have existed, the fruits of seed plants have evolved into the most efficient seed distributors. What you see around you today, in nature, are the plants that are the fittest in terms of reproduction. Of course there are also cultivated plants that have been bred by humans to produce what other humans consider the most desirable characters. Excluding the latter, we are left with the plants that have evolved to exist successfully, molded by the physical and biological forces of nature. Take the acorn as an example. If it germinated directly under the parent oak, it would have to compete for sunlight and water. Acorns are rounded and tend to roll on the ground when they fall, thus taking them a reasonable distance from the sun-robbing parent. Willows and poplars have seeds attached to wispy, cottony parachutes, which allow them to fly with the wind to areas distant from the parent plant. Maples and pine seeds have the little wings that also allow them to drift in the winds to distant places. Some trees have flowers with both male and female parts, others have flowers with only male or female parts and yet others have female flowers on one plant, and male flowers on another. A perfect example of the latter is the holly where only the female plant bears berries but a male plant must be nearby to provide the pollen. Other plants must have insects that frequent their blossoms to spread the pollen from one flower to another in order to bear fruit. Direct evidence of this are plants that are imported from other lands, without their pollinating insects, and therefore never bear fruit. But when we focus on the tree seed itself, it holds in its tiny form the beginnings of a new plant and the genetic instructions that will make sure that it is a tree. We expect when we plant an acorn we will get an oak tree and not something else. As simplistic as this may sound, it is a basic concept that children need to understand, as we infer by its inclusion in the Standards. We can also expect that any tree seed, including that of a gymnosperm, will germinate approximately the same way that any angiosperm will germinate. We will see some form of plant tissues that will provide food to the young seedling until it can photosynthesize its own food. We will see primitive roots and stems

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Chapter 5

and it will require sunlight, water, and rich soil to thrive. Only rarely does a seed need sunlight to germinate. It needs only a nurturing environment with moisture and warmth to begin its life as a growing plant. The little plant begins its growth while in the seed and once it germinates, it merely continues its growth. Once it has established itself in a good environment, it is on its own, to grow and produce flowers, fruits, and seeds when it reaches maturity. Oak seeds, acorns, have nutritional value and have been used for centuries by native people and others who know how to treat them to remove the tannin, which is bitter and prevents the absorption of nutrients in mammalian digestive tracts. It turns out that white oak acorns have less fat content and sprout in the fall so that they are not the best acorns for squirrels to store. If the acorn begins to germinate its nutritional value becomes less. Red oak acorns have more fat but have more tannin and can be stored for the winter, but the tannin will affect the absorption of the nutrients in the squirrels’ digestive tracts. As you can see, it is a balancing act as to which acorn provides the most nutrition. The squirrels seem to prefer the acorns that do not germinate immediately even though the tannin makes them less digestible and I suspect, less tasty. But then who knows if squirrels are gourmets. Molds are a primary enemy of germinating seeds. Rinsing seeds in a chlorine bath can often help prevent the growth of mold, but you will have to be on constant lookout for mold on your germinating seeds and young seedlings during the two to three weeks it might take to germinate. For safety reasons, you to use the chlorine bath instead of having the children do so.

Related Ideas From the National Science Education Standards (NRC 1996) K–4: The Characteristics of Organisms

• Organisms have basic needs. For example, plants require air, water, nutrients and light. • Each plant or animal has different structures that serve different functions in growth, survival, and reproduction.

K–4: Life Cycles of Organisms

• Plants and animals have life cycles that include being born, developing into adults, reproducing, and eventually dying. The details of this life cycle are different for different organisms. • Plants and animals closely resemble their parents

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6–8: Life Cycles of Organisms

• All organisms must be able to obtain and use resources, grow, reproduce and maintain stable internal conditions while living in a constantly changing external environment.

Related Ideas From Benchmarks for Science Literacy (AAAS 1993) K–2: Cells

• Most living things need water, food, and air.

K–2: Flow of Matter and Energy

• Plants and animals both need to take in water, and animals need to take in food. In addition, plants need light.

K–2: Agriculture

• Most food comes from farms either directly as crops or as animals that eat the crops. To grow well, plants need enough warmth, light, and water.

3–5: Flow of Matter and Energy

• Some source of energy is needed for all organisms to stay alive and grow.

3–5: Agriculture

• Some plant varieties and animal breeds have more desirable characteristics than others, but some may be more difficult or costly to grow.

6–8: Flow of Matter and Energy

• Food provides the fuel and building material for all organisms. Plants use the energy from light to make sugars from carbon dioxide and water. This food can be used immediately or stored for later use.

6–8: Agriculture

• People control the characteristics of plants and animals they raise by selective breeding and preserving varieties of seeds (old and new) to use if growing conditions change.

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Chapter 5

Using the Story With Grades K–4

You may find that giving the probe “Needs of Seeds” from Uncovering Student Ideas in Science, Volume 2 (Keeley, Eberle, and Tugel 2007) will provide you with valuable information on what kind of preconceptions your students bring to your class. Maple seeds, as many of us have found, can germinate immediately after falling from the tree. Questions will arise about how to plant these “wild” tree seeds and of course, from these questions arise the hypotheses and experiments for which we aim in teaching for inquiry. Oaks are a different story. If you can identify the white oak acorn they can be planted immediately. The best way to identify them is to identify the tree and harvest acorns from beneath the tree. For your information, they do best if planted about one inch below the surface of the soil. They send out a particularly long tap root (7.5 cm,) so it should be planted in an appropriately tall container with a hole in the bottom for drainage. When collecting acorns, be aware many are not healthy and harbor a tiny wasp larva, which feeds on the food inside. You may ask the children if they think the acorns will float. All will float if the cap is still left on. If you can remove the cap easily, the acorn is mature. A few minutes soaking in a weak bleach solution (½ cup of bleach to a gallon of water) will kill any mold that may be on the acorn. (Caution! The teacher should do this.) When they have made their predictions, put the acorns in a container of water and you will see that some will float and others will sink. The sinkers are the viable ones; the floaters have lost much of their mass due to infestation or lack of a viable seed and the food reserve for the young seedlings. You may want to cut them open and see what is inside and should be rewarded with some insect larvae or other organisms that are eating away at the nutritious food. The sinkers are dense with a seed and food and should germinate. These can also be cut open, and it is much easier to do so if they are soaked over night. In fact, when you are ready to plant acorns, it is a good idea to soak them overnight as well. With young children, you may want to place your chosen seeds in a wet paper towel and place them in an open plastic bag so that the children can check on them periodically to see what is happening to the germinating seeds. One does not necessarily have to stick to the germination theme if the students become interested in, for example, which acorns do squirrels prefer, or more appropriately, do squirrels prefer one or two acorns over others? Also, students may wonder what is inside the acorn and when dissected, they may find a whole community of living things. Their interest may also shift to the seeds of the gymnosperms or so-called conifers and their naked seeds. You may be amazed at the number of questions about these everyday items that will arise once they are involved in dialog about them. How are cones different from fruits? Do pine seeds need to be cooled like acorns? What kind of soil do they like best? How are they different from seeds that are found in fruits? How long does it take for various seeds to germinate? How deep should we plant them and in what position? What is the purpose of the little cap on the acorn? Do we need to plant the cap too?

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The questions can be endless and with your help the students can design many experiments and learn a great deal about these everyday, yet mysterious objects. Remember, since experts still disagree on exactly how to germinate tree seeds, your students may well be collecting data on questions that are still open.

Using the Story With Grades 5–8 I advise teachers of these grades to read the above passages on grades K–4 since

many ideas may be common to both levels. Also some of the techniques mentioned will be important for you to know. Students of this age may have more sophisticated questions to place on the class chart and may be able to develop more sophisticated experiments. You will also find that giving the probe “Needs of Seeds” from Uncovering Student Ideas in Science, Volume 2 (Keeley, Eberle, and Tugel 2007) will provide you with valuable information on what kind of preconceptions your students bring to your class. Testing with this probe has taught us that some students will say that seeds need food to germinate because they are aware of the nutritional substance in the seed as food. Probing will tell you if they are thinking of this kind of food or additional food that has to be added. One question that may come up is, “What kinds of acorns do animals prefer to eat?” Your students can design experiments, which involve placing several kinds of acorns in an area and keeping data on which kind are taken. Be sure to use only viable acorns since animals usually do not take acorns that are not healthy. This might best follow a dissection of seeds so that your students can discover that some acorns have inhabitants and are damaged. While dissecting a mature acorn, you may want to soak the nut in water overnight to make the dissection easier. Look for the plant inside by making a longitudinal cut. This should be done by adults, in a manner that will not let the round nut turn and injure them. It is also a good idea to consider gently using a nutcracker to get the tough outer coat of the nut broken and open for business. The main question to be asked of the fruit you see is, “How do you help the seeds you enclose, get to where they can best germinate, and produce new plants?” Secondary questions would be, “Are you tasty, so that you attract animals that eat you or bury you and thus spread your seeds far from the original tree? Do you pop open and propel your seeds or do you produce little parachutes so that they can fly in the wind? Are you shaped like tiny helicopters so that the wind can carry you? Do you have a hard protective case so that you protect your seeds from inclement weather? Do you have a Velcro-like surface on you so that you stick to animals’ fur or feathers and travel great distances from your mother plant?” You may remember the technique described in background material of the story “Oatmeal Bugs,” (see Chapter 24) specifically the game “What Does it Tell You, What Do You Want to Know?” It would work well here as well. If there are oaks and maples near your school and they have low branches, you may be able to see the flowers on the trees on a 10-minute field trip. In maples, the flowers often appear in the spring before the tree has leafed out and will give

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Chapter 5

the tree a red lacey kind of appearance. Oaks will produce their flowers later and the acorns will not be viable until the fall. Using both trees in your study will test your flexibility in beginning a unit in the fall and returning to it in the spring but it will be well worth the effort.

Related Books and Journal Articles Cavallo, A. 2005. Cycling through plants. Science and Children 42 (7): 22–27

Driver, R., A. Squires, P. Rushworth, and V. Wood-Robinson. 1994. Making sense of secondary science: Research into children’s ideas. London and New York: Routledge Falmer. Keeley, P. 2005. Science curriculum topic study: Bridging the gap between standards and practice. Thousand Oaks, CA: Corwin Press. Keeley, P., F. Eberle, and L. Farrin. 2005. Uncovering student ideas in science: 25 formative assessment probes, volume 1. Arlington, VA: NSTA Press. Keeley, P., F. Eberle, and J. Tugel. 2007. Uncovering student ideas in science: 25 more formative assessment probes, volume 2. Arlington, VA: NSTA Press. Quinones, C., and B. Jeanpierre. 2005. Planting the spirit of inquiry. Science and Children 42 (7): 32–35. West, D. 2004. Bean Plants: a growth experience. Science Scope 27 (7): 44–47.

References American Association for the Advancement of Science (AAAS). 1993. Benchmarks for science literacy. New York: Oxford University Press. Keeley, P., F. Eberle, and J. Tugel. 2007. Uncovering student ideas in science: 25 more formative assessment probes, volume 2. Arlington, VA: NSTA Press. National Research Council (NRC). 1996. National science education standards. Washington, DC: National Academy Press. Pollan, M. 2001. Botany of desire. Toronto: Random House.

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Chapter 6

Trees From Helicopters, Continued

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N

ot quite a year had passed since Eric and Sarah had swept the maple fruits from the porch at their mother’s request. They had brushed the tiny helicopters from the red maple carefully into a bag so they did not fall into the garden, germinate, and grow into little maple trees in the midst of the other flowers. Eric and Sarah were now sweeping up little red things off the porch. These were different from the year before: little, lacey, red, flowerlike objects that absolutely covered the porch floor. Eric and Sarah had not paid much attention to them previously except to moan and groan since they had a chore they did not enjoy much. Again they were told to be careful not to sweep them into the garden. They remembered that last year they had wondered about the tiny helicopters from the maple tree and were a bit surprised when they discovered that the maple tree actually had flowers. They had found out that the helicopters were fruits of the tree that contained seeds that could germinate. They also recalled that they were amazed to find out that other trees had flowers and fruits that they had never noticed. But these new red things were different. First of all, they did not float to the ground like helicopters, did not have wings, and were red and flimsy. No, these were definitely something else entirely. Sarah was the first to notice that the maple tree next to the house still had many of the little red objects on them and that they were merely falling off the tree without the benefit of a wing or the wind. “Eric, we have another mystery on our hands. These come from the same maple tree as the helicopters last year did, but they are entirely different.” “Well, we still have to sweep them off so they don’t turn into trees,” said Eric. “Maybe not,” said Sarah. “They don’t look like they are going to sprout into anything. Maybe they just make a mess and we can sweep them anywhere.” “Well, Miss Sherlock Holmes wannabe, let us go even now unto the tree and see what we can see!” Eric liked to talk like a poet sometimes just to be funny. But Sarah had heard enough of this kind of talk not to be amused. “Okay, Eric, my boy, good idea. Let’s go look at that low-hanging branch over there.” There, in miniature form were all of the data they needed in order to solve their new mystery. Neither Eric nor Sarah, who had lived next to that tree for a number of years, had ever noticed these little red things before. But whatever they were, thinking and wondering about them made the job of sweeping the porch a lot more interesting and easier for the two children, so they were grateful.

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Purpose Maples are very interesting trees with lots of variation in form. They provide us

with a view of diversity in plants as well as a chance to look at natural phenomena that is very common to anyone who has had a maple tree near them. The main purpose is to allow students to examine what happens in the reproductive life of trees. This is indeed a fascinating everyday science mystery. After all these years of sweeping our porch covered with these common objects, it was only this year that I stopped ignoring them and took the time to really observe what the tree was producing! I found I could watch the formation of the maple fruits take place day by day and begin to understand the complexities of this phenomenon. This activity also provides an excellent opportunity for students to observe, draw, and describe in their science notebooks the changes that take place over time.

Related Concepts • Diversity • Pollination • Life cycles

• Reproduction • Living things • Structure and function

Don’t Be Surprised Unless your students have seriously been involved in an activity such as “Adopt a Tree,” it is unlikely that they have noticed the complex way in which the maple tree and others of its family produce their fruits and the enclosed seeds. Many students will not be aware that trees other than fruit trees have flowers and produce fruits. Even those students who are aware of the role of flowers in the reproductive process will surely be surprised and intrigued by what they see on the maple branches in the early spring, especially examining the differences between the imperfect (male and female) flowers. You may also be taken aback to find that some of your students do not think that trees are plants.

Content Background Maples belong to the family Aceraceae. There are about 120 species of maples in

the United States. They have a very large range, found from central Florida almost to the Arctic Circle. For observational purposes, red maples (also known as swamp maples) are probably the most common east of the Mississippi, but there are also sugar maples, famous for their wonderful syrup made from the high sucrose sap of the tree in the springtime. Other maples are found in the west, such as the big leaf maple in California and the Rocky Mountain maple in the Colorado area. The box elder is in the same family and is found in all 48 states and much of Canada. All

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Chapter 6

belong to the genus Acer; the many species will differ slightly in their leaves and flowers, but all the members of the genus will provide winged fruits. Before the leaves come out in the spring, the flowers of the maple are very evident on the tree. First come the male flowers, which, in the case of the red maple, are bright red, with only stamens (the organs with pollen). Shortly after or nearly at the same time, the female flowers appear. They are on long droopy stalks that contain only pistils (which hold the ovaries) ready to receive the male pollen. Pollen lands on the top of the pistil, called a stigma. The sperm in the pollen make their way through a tube to the female ovule to fertilize it and begin the formation of the seed. Although maples are pollinated by the wind blowing the tiny pollen grains, insects that frequent both male and female flowers to drink the nectar or collect some pollen also help the process by spreading the pollen. Plants may be either monoecious or dioecious. Monoecious organisms have both male and female reproductive parts on one plant or animal and dioecious organisms have male and female reproductive parts on separate animals or plants. My particular pet maple, the red maple, happens to be monoecious and has both male and female flowers on the same tree. However, the male flowers usually come from buds on the side of the branch and the female flowers from the buds on the tip of the twig. But this may vary from tree to tree. Figure 6.1 Male Maple Flowers: Male Acer rubrum

Also in my garden (and maybe in yours) is a holly bush, which is a common dioecious plant. In order for the female holly bush to produce the red berries there must be a male tree nearby. In many cities, a common dioecious tree is the gingko, an ancient and very beautiful tree. Most of the rest of the plants, however, are monoecious and have flowers with both male and female parts. A picture of each kind of flower is found in Figure 6.2.

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Figure 6.2 Female and Male Holly Flowers: Ilex aquilifolium

Chapter 6 Nonfunctional anthers

Anthers with pollen

Pistil

Female (Pistillate)

Male (Staminate)

The chore given to the children was to sweep up the male flowers that fall to the ground after their time on the tree is finished. The female flowers that have been pollinated remain on the tree to produce the fruits that contain the seeds. Your students, after they have done some careful observations, will notice that the fruits are visible there, with their tiny seeds and tiny wings. The red stuff on the ground and porch Sarah and Eric had swept away are not capable of producing trees in the garden. Some of them may also be female flowers that have not been pollinated, but they are no danger either since they contain no seeds. But soon the winged fruits will be falling and the next sweeping will be a bit more difficult. But this time, they can tell Mom that they do not have to be so careful about where they sweep the flowers. Figure 6.3 Female Maple Flowers: Acer rubrum Stigma

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As you can see by the drawing in Figure 6.3, the tiny immature fruits are like miniatures of the mature fruits with which we are so familiar. For those who have not done “Trees From Helicopters” (see Chapter 5), it is important to note that the winged objects that fall from the trees are really fruits with seeds at the base. The ovary of the female flower has produced the seed; the wing attachment covering the seed is part of the fruit. We often refer to the winged fruits as seeds but this is not correct since the seed is only a part of the entire winged fruit. In fact, all flowering plants, called angiosperms, produce fruits within which lie the seeds. On the tree, once the egg has been fertilized and the seed formed, your students will see the seed and the beginning of the wing that will function later to carry the seed away from the parent tree by wind. Fruits with wings are called schizocarps. If your students begin watching early enough in the process, immediately after the staminate flowers begin to drop off the tree, they will be able to witness the growth of the tiny wings into full-size wings; and they will see the stalk to which the fruit is attached elongate in order to bring the schizocarp far away from the tree branch so it can catch the wind effectively.

Related Ideas From the National Science Education Standards (NRC 1996) K–4: The Characteristics of Organisms

• Organisms have basic needs. For example, plants require air, water, nutrients, and light. • Each plant or animal has different structures that serve different functions in growth, survival, and reproduction.

K–4: Life Cycles of Organisms

• Plants and animals have life cycles that include being born, developing into adults, reproducing, and eventually dying. The details of this life cycle are different for different organisms. • Plants and animals closely resemble their parents.

6–8: Life Cycles of Organisms

• All organisms must be able to obtain and use resources, grow, reproduce, and maintain stable internal conditions while living in a constantly changing external environment.

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Related Ideas From Benchmarks For Science Literacy (AAAS 1993)

Chapter 6

K–2: Diversity of Life

• Some animals and plants are alike in the way they look and in the things they do, and others are very different from one another. • Plants and animals have features that help them live in different environments.

K–2: Heredity

• There is variation among individuals of one kind within a population. • Offspring are very much, but not exactly, like their parents and like one another.

K–2: Interdependence of Life

• Living things are found almost everywhere in the world. There are somewhat different kinds in different places.

3–5: Diversity of Life

• A great variety of kinds of living things can be sorted into groups in many ways using various features to decide which things belong to which group. • Features used for grouping depend on the purpose of the grouping.

3–5: Heredity

• Some likenesses between children and parents such as eye color in human beings, or fruit or flower color in plants, are inherited. Other likenesses, such as people’s table manners or carpentry skills, are learned. • For offspring to resemble their parents, there must be a reliable way to transfer information from one generation to the next.

3–5: Interdependence of Life

• For any particular environment, some kinds of plants and animals survive well, some survive less well, and some cannot survive at all. • Organisms interact with one another in various ways besides providing food. Many plants depend on animals for carrying their pollen to other plants or for dispersing their seeds.

6–8: Diversity of Life

• Animals and plants have a great variety of body plans and internal structures that contribute to their being able to make or find food and reproduce. • For sexually reproducing organisms, a species comprises all organisms that can mate with one another to produce fertile offspring.

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6–8: Heredity

• In sexual reproduction, a single specialized cell from a female merges with a specialized cell from a male. As the fertilized egg, carrying genetic information from each parent, multiplies to form the complete organism with about a trillion cells, the same genetic information is copied in each cell.

6–8: Interdependence of Life

• In all environments—freshwater, marine, forest, desert, grassland, mountain, and others—organisms with similar needs may compete with one another for resources, including food, space, water, air, and shelter. In any particular environment, growth and survival of organisms depend on the physical conditions.

Using the Story With Grades K–4 You may like to start your lesson with a probe from Uncovering Student Ideas in

Science, volume 2 (Keeley, Eberle, and Tugel 2007) called “Is It a Plant?” It is good to know what your students consider to be plants, and sometimes you can be surprised to find out that trees do not fit into their definition. Another possible probe is “Does It Have a Life Cycle?” from Uncovering Student Ideas in Science, volume 3 (Keeley, Eberle, and Dorsey 2008). Both probes will give you a formative assessment of how your students view two different concepts involving plants and life cycles. This can definitely affect the way in which you approach the topics. I like to start with a chart where children tell me what they “know” about trees and especially about how they make seeds. This chart is called “Our Best Thinking Until Now” and can be modified as the lessons progress. Many of you may have used the old favorite exercise “Adopt a Tree” with your students. In this, students become acquainted with a tree by taking its picture over the seasons and making journal entries about changes that occur, thus observing the tree closely and getting to know it. It is a great activity because unlike other biological specimens, a tree is always where you left it, available for scrutiny. The seasonal changes make observations interesting. Patience and careful examination are necessary to get the full amount of information available. For this particular story, it is important that you identify a maple or box elder in the general vicinity of the school or find out if your students are aware of a maple tree in their home areas. Parental help may be useful here. Of course it is important to begin this study at the right time of the year. You can find out when the maples or elders put out flowers in your area by doing some research on the internet or asking local experts. Once the tree or trees are found, it is important for the students to begin keeping a science notebook on this topic. They will need help in planning how they are going to observe their tree and how they are going to record data. Their

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notebooks would include drawings of the flowers, labeled with dates and a method of including measurements in the drawing. With the number of digital cameras available today, photographing the flowers with a small metric ruler in the picture is an excellent method of recording data. If you desire students to draw, they can use the photograph shown on a computer as a model. My experience is that drawing pictures of objects helps students focus on details that might be missed if they merely look at a photograph. One drawing might suffice with the data for subsequent measurements entered in tabular form. With younger students, merely drawing the flowers and fruits as they develop would be enough to help them show the differences in growth and changes in shapes and colors. When the fruits fall from the tree, those that can be germinated without a freezing period can be planted or placed in plastic bags so that the germination can be observed. See your local plant guides for requirements for germination in your section of the country. Some seeds need six months of cold in order to prepare them for germination while others, like the red maple, germinate immediately. The intriguing thing about the development of the winged fruits is how they begin as miniature forms with the tiny wings attached to the immature fruit. The wings grow larger and larger until the fruit is ready to be disseminated. Being able to watch this daily (or, perhaps better, weekly) growth is both fascinating and informative. Maturing fruits of all sorts can, of course, be observed during the school year in climates where growing seasons last all year. In temperate climates, however, school is usually not in session during the time that squash or tomatoes, for example, ripen from the pollinated flower. Home schoolers can take advantage of this phenomenon at any time of the year due to their yearlong curriculum. There may be a great number of “what ifs” that could be used with the fruits. For example: • What if the fruit were to be planted without the wings? • What if the fruit were to be placed just in water without soil? • What if the fruit were to be planted before it was ready to leave the tree on its own? • What if the female flower had a plastic bag placed over it as soon as it developed? Would it still develop a fruit? I am sure that your students can come up with a lot more “what ifs” and thereby develop their own inquiry-based investigations about the formation of the fruits.

Using the Story With Grades 5–8 Many of the above ideas are also useful for older students. However, older students

are more familiar with measurement and can carry out data gathering on their own more readily. Questions may arise on how fast the fruit wings grow or how long it takes the fruit to mature. Many questions can be asked about the flowers and pollination, such as:

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Chapter 6

• What would happen if some of the female flowers were bagged and prevented from being pollinated? • Do they notice any insects visiting the flowers and if so, what kinds of insects are doing the pollinating? • At what point do the male flowers fall off the tree? • Do male and female flowers appear at the same time in your tree? • Is your tree monoecious or dioecious? • Is there any difference between the flowers of each kind of tree (male and female)? • Do monoecious and dioecious trees put out their flowers at the same time? Other questions might arise with the following scenario. First, the seed is formed after pollination and fertilization, then the fruit is formed with wings and covering. Is the seed “ripe” enough to germinate before the wings are fully formed? Sounds like a research question or two in there somewhere! When you look at the young fruit developing, it looks as though the seed is fully formed, but is it? One might dissect the seeds and compare the fully formed ones with the young ones or run a germination test. The question then becomes, “Do the seeds remain on the tree only because of the need for the wings for dissemination?” I am sure that your students can find many more questions that pop into their minds about this intriguing tree. What could be the value of having two different types of flowers on the same tree or on separate trees? Some questions are good food for discussion but not necessarily for experimentation. The internet has tons of information on the particular maple or box elder that is in your location.

Related NSTA Press Books and Journal Articles Driver, R., A. Squires, P. Rushworth, and V. Wood-Robinson. 1994. Making

sense of secondary science: Research into children’s ideas. London and New York: Routledge-Falmer. Keeley, P. 2005. Science curriculum topic study: Bridging the gap between standards and practice. Thousand Oaks, CA: Corwin Press. Keeley, P., F. Eberle, and L. Farrin. 2005. Uncovering student ideas in science: 25 formative assessment probes, volume 1. Arlington, VA: NSTA Press. Keeley, P., F. Eberle, and J. Tugel. 2007. Uncovering student ideas in science: 25 more formative assessment probes, volume 2. Arlington, VA: NSTA Press. Keeley, P., F. Eberle, and C. Dorsey. 2008. Uncovering student ideas in science: Another 25 formative assessment probes, volume 3. Arlington, VA: NSTA Press.

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References American Association for the Advancement of Science (AAAS). 1993. Benchmarks for science literacy. New York: Oxford University Press. Keeley, P. 2005. Science curriculum topic study: Bridging the gap between standards and practice. Thousand Oaks, CA: Corwin Press. Keeley, P., F. Eberle, and C. Dorsey. 2008. Uncovering student ideas in science: Another 25 formative assessment probes, volume 3. Arlington, VA: NSTA Press. Keeley, P., F. Eberle, and L. Farrin. 2005. Uncovering student ideas in science: 25 formative assessment probes, volume 1. Arlington, VA: NSTA Press. Keeley, P., F. Eberle, and J. Tugel. 2007. Uncovering student ideas in science: 25 more formative assessment probes, volume 2. Arlington, VA: NSTA Press. Konicek-Moran, R. 2008. Everyday science mysteries: Stories of inquiry-based science teaching. Arlington, VA: NSTA Press. National Research Council (NRC). 1996. National science education standards. Washington, DC: National Academies Press.

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Chapter 6

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Chapter 7

Flowers: More than Just Pretty

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O

livia had a bouquet of flowers in her hand, all ready to give them to her mother for Mother’s Day. There were daisies, peonies, lilies, and a few flowers she had never seen before. One thing Olivia noticed was that they were all different in one way or another. Not just in color but also in the way they were shaped and the way their little parts were arranged. Kathleen was in the florist’s shop with Olivia and was admiring the flowers too. “Those will look very pretty on the kitchen table in a vase,” said Kathleen. “Yeah, I hope they are fresh and will last a few days,” answered Olivia. “They always seem to die so quickly when you put them in a vase of water, but outside they last for a long time.” “You know,” said Kathleen, “our teacher said that everything in nature has a purpose. Now what do you suppose the purpose of flowers is? Just to look pretty when you pick them and put them in a vase? “It must be more than that,” said Olivia. “Ms. Washington said that flowers on plants have been on Earth a lot longer than people have, so who would pick them? Chimpanzees?” “I think chimps would be more likely to eat them than pick them for decorations,” said Kathleen. “I know that my mom says that people eat some flowers, like in salads and things like that. And I think that broccoli and cauliflower are bunches of flower buds that haven’t opened yet and we eat them. I think maybe asparagus, too.” “Yeah, well, maybe you eat broccoli but I avoid it whenever I can, even though everybody says it is sooooo good for me.” “Well, flowers must be good for more than food for people and bugs,” said Olivia. “But why are they all so different? Like the daisies with all of those petals around the edge. They look like tiny sunflowers with the petals shining like sunlight around the middle button. And the lily with just a few petals that almost look like one big petal or like a cup full of little stalks. And they all seem to have a lot of little parts that don’t make a lot of sense to me, like these things on a stalk that come out of the middle of the lily. The daisies don’t have them! Or do they?” “I don’t know,” said Kathleen. “I’ll have to look closer. Maybe I can borrow a magnifying glass to get a better view. I think I may need a little help though since I’m not sure what all of these parts are for even after I do get a closer look at them. Maybe if we looked at them while they were still on the living plants we could find out what they do.” “Good idea,” said Olivia,” but I had better get these home now to Mom before they don’t look as good as they do now.”

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Purpose Children love to look at flowers but few are inclined to become familiar with

the structure and function of the flower. This story is aimed at providing some motivation for children to learn about one of the most important evolutionary developments in the plant and animal world. The students will also develop skills to help them decipher the purpose of these fascinating structures and the fruits that emerge from them.

Related Concepts • Reproduction • Pollination • Seeds

• Fertilization • Fruits • Insects

Don’t Be Surprised Children may not be aware of the continuity of life in their world. They may, for

example, think that seeds are dead and not a part of a continuum of flower-seedplant-flower-seed, and so on. Most are not aware of the importance of variation in the plant and animal world in developing new species or how sexual reproduction enhances the chances of new attributes being found in a population of organisms. Many will not be aware that plants can be either male or female, nor will they be aware of the role of other organisms in the cross-pollination of flowers. Working within this story framework will give you plenty of opportunity to address these concerns. These ideas are expanded and explained in the following section.

Content Background Something amazing happened approximately 150 million years ago on Earth. Plants

developed the reproductive structures we call flowers, which, in the beginning, relied on the wind to spread their pollen. In the centuries that followed, insects (probably beetles) helped flowers pollinate each other, while the plants provided food for the insects. Nice trade-off! Scientists are still looking for the first flower in fossil form but as yet have not agreed on which one of the specimens found thus far is the first. About 85 million years later, butterflies, bees, wasps, and moths had evolved and joined in the flower-insect relationship. This evolutionary change in how plants reproduced altered the biological world forever. But let’s backtrack for a moment, and set the scene for the emergence of flowering plants (which are called angiosperms). Scientists believe that mosses were the first plants to inhabit the land about 435 million years ago, followed by ferns, ginkgos, and then by the cone-bearing plants: the conifers. Up to that point, the mosses

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Chapter 7

and ferns produced spores that were carried either by water or wind in order to perpetuate the species. The ginkgos and conifers, being more complex, had windblown male reproductive cells that fertilized female structures, thus producing seeds not protected by fruits. These are known as the gymnosperms (“naked seed” in Latin). But, on the whole, pollination by these vectors was a rather hit-or-miss affair. Then the flowering plants appeared in fossil records. Scientists are still researching about how they could have erupted so suddenly and why they came into prominence. They surmise that the introduction of flowers took sexual reproduction in plants one step beyond where it had been before, because angiosperm seeds are protected inside the female organ, the ovary. This ovary swells, produces a fruit that safeguards the seeds, and is an attractive food for animals, which help spread seeds. Angiosperm seeds were no longer destined to be naked but fully “clothed” and therefore more successful. It is likely that the development of flowers had a strong effect upon the evolution of insects. Many plants had moved from depending upon wind to spread their pollen to depending upon insects traveling from flower to flower to spread their pollen, thereby spreading their genes beyond themselves. Flowers developed tissues that produced sugar-rich nectar at the bottom of the petals, and brilliant colors or an alluring fragrance to attract pollinators. Insects then developed a sweet tooth, a sense of smell, or color awareness, therefore finding flowers attractive places to visit. The insects get nourishment (most of the time) and the flowers get genetic diversity. This mutual bond continues to grow even today as flowers and insects evolve to become more compatible to each other’s needs. In some cases, flowers have evolved shapes that make it challenging for the insects to enter their depths, the resulting struggle through narrow chambers making it more likely that pollen will become attached. Flowers now have brighter colors and stronger fragrances. Although it is difficult to realize that the flowers are not pretty or fragrant for our delight, we are now finding many more ways the elements of their beauty attract specific kinds of insects. Bees, for example, do not see red but they do see blue and yellow. Therefore, blue and yellow bee-pollinated flowers are most likely to survive. We also know butterflies can see red, but have a poor sense of smell, so they frequent red flowers. Bees are fond of pollen as food and collect it on their legs to transport back to the hive. As they move from flower to flower, some of the pollen is dropped or scraped off and the “goals” of the flower and the insect are realized. In some orchids, the goal is not nectar or pollen, but sex! Some flowers have evolved to look like the mating end of another bee. When the amorous bee tries to mate with the false flower “bee,” the top of the flower is forced down, dabbing pollen on the back of the now frustrated bee, who moves on to another orchid to try again. Luckily for the flowers, bees learn slowly! So in essence, the insects and flowers evolve together to work toward greater success for each of the organisms involved. As a result of this fascinating process, both flowers and insects have developed what we might consider bizarre structures to accomplish the fulfillment of the needs of both parties. [David Attenborough has produced a series of films profiling the

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process in his series for the BBC The Private Life of Plants. It is available now on DVD and cassette from most distributors. This is a must-see program.] The form of flowers and the parts that make up the flower are important because of their functions. Pollen contains the male cells that connect with the external female structure of the flower. This is called pollination and is often confused with fertilization but is quite different. Fertilization takes place when the male reproductive cell unites with the female egg or ovule inside the ovary to form a zygote, which will eventually become a seed. As we noted before, insects, wind, or birds may contribute to pollination by transporting pollen to another flower of the same species. Some flowers, such as the dandelion, may self-pollinate, but usually only as a last resort. One important thing to do is to take a look at what flowers have in common and what makes some of them unique. Flowers that rely upon wind for pollination are usually not showy since they do not have to attract insects or birds to distribute their pollen. Flowers that are showy and fragrant have adapted to attract an animal to distribute their pollen. A diagram of a simple flower is shown below (Figure 7.1) and the function of each part will be described next. Figure 7.1 Diagram of a Complete Flower

Stigma

Stamens Pollen (on anther)

Petal

Sepals

Pistil

Ovary Ovule

You will notice that the base of the flower (the calyx) is made up of sepals, which are not usually showy but protect the bud before the flower opens and may even fall off once the bud opens. Above the calyx is a whorl of petals, which are usually the pretty part of the flower, colorful in order to attract pollinators. The petals and sepals together are called the corolla and surround the reproductive structure(s) within. Usually in the center is the pistil or carpel (as it is often called in texts), which is comprised of the ovary near the base of the flower containing the ovules that when fertilized will become seeds. Notice the style, an erect column above the ovary and finally the stigma, atop the style, to which the pollen grains adhere. Ranging around the central pistil are the stamens, composed of the filaments or stalks that culminate in the anthers from which pollen emanates. You may notice that the anthers are lower than the pistil so self-pollination is more difficult. The main point is that

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Chapter 7

Figure 7.2 A Complete Balloon Flower: Platycolon grandiflora Corolla (all the petals) Calyx (all the petals) Sepal Petal

Pistil Stamen

Leaf Stem

Figure 7.3 Female and Male Holly Flowers: Ilex aquilifolium Nonfunctional anthers Pistil

Female (Pistillate)

Anthers with pollen

trading pollen with other flowers makes genetic variation more probable and makes the production of new varieties more likely. Plants go to great lengths to avoid self-pollination. For instance, some stigmas just do not allow their own pollen to enter the pistil, or flowers ripen their sexual parts at different times. Flowers that have both of the reproductive parts (pistils and stamens), petals, and sepals are said to be complete or perfect flowers. If a flower has any of these parts missing it is called incomplete or imperfect. Male flowers are called staminate flowers because they have functioning stamens but no functioning pistils. If the children look carefully at, say, a maple tree, they will find pistillate flowers because the flowers that remain on the tree are the female flowers with functional pistils but either no stamens or nonfunctional stamens. When pollen lands and sticks to the stigma on the pistil, it produces several nuclei within itself. One is a tube nucleus that bores into the style and works its way down to the ovary. The other is a male germ cell, which divides into two sperm cells that travel down the tube, where one merges with the female egg to form the zygote that will become the seed. The second sperm unites with other cells in the ovary to form the endosperm. This provides nutrition for the growing embryo. The ovary wall then develops into the fruit, which encloses the seed(s). In some plants there are multiple eggs in the ovary and multiple male cells to produce fruits with lots of seeds such as berries, corn, or peas. For an incredible set of pictures, diagrams, and explanation of this process go to www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookflowersII.html. Floral reproduction is an amazing and marvelous process, besides giving us the joy of flowers’ beauty. Flowers and their impact on their pollinators are vital to the ecosystems of the world. Understanding floral structure and reproduction could be the beginning of a lifelong fascination with evolution through genetic diversity.

Male (Staminate)

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Related Ideas From the National Science Education Standards (NRC 1996) K–4: The Characteristics of Organisms

• Organisms have basic needs. For example, plants require air, water, nutrients and light. • Each plant or animal has different structures that serve different functions in growth, survival, and reproduction.

K–4: Organisms and Environments

• All organisms depend on plants. Some animals eat plants for food. Other animals eat animals that eat the plants. • An organism’s patterns of behavior are related to the nature of that organism’s environment, including the kinds of numbers of other organisms present, the availability of food and resources, and the physical characteristics of the environment. When the environment changes, some plants and animals survive and reproduce, and others die or move to new locations.

K–4: Life Cycles of Organisms

• Plants and animals have life cycles that include being born, developing into adults, reproducing, and eventually dying. The details of this life cycle are different for different organisms. • Plants and animals closely resemble their parents.

6–8: Life Cycles of Organisms

• All organisms must be able to obtain and use resources, grow, reproduce and maintain stable internal conditions while living in a constantly changing external environment.

6–8: Structure and Function in Living Systems

• Living systems at all levels of organization demonstrate the complementary nature of structure and function. Important levels of organization for structure and function include cells, organs, tissues, organ systems, whole organisms and ecosystems. • Specialized cells perform specialized functions in multicellular organisms. Groups of specialized cells cooperate to form a tissue, such as a muscle. Different tissues are in turn grouped together to form larger functional units, called organs. Each type of cell, tissue, and organ has a distinct structure and set of functions that serve the organism as a whole.

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Chapter 7

6–8: Reproduction and Heredity

• Reproduction is a characteristic of all living systems; because no individual organism lives forever, reproduction is essential to the continuation of every species. Some organisms reproduce asexually. Other organisms reproduce sexually. • In many species, including humans, females produce eggs and males produce sperm. Plants also reproduce sexually—the egg and sperm are produced in the flowers of flowering plants. An egg and sperm unite to begin development of a new individual. That new individual receives genetic information from its mother (via the egg) and its father (via the sperm). Sexually produced offspring never are identical to either of their parents.

6–8: Regulation and Behavior

• An organism’s behavior evolves through adaptation to its environment. How a species moves, obtains food, reproduces, and responds to danger are based in the species’ evolutionary history.

6–8: Diversity and Adaptations of Organisms

• Millions of species of animals, plants, and microorganisms are alive today. Although different species might look dissimilar, the unity among organisms becomes apparent from an analysis of internal structures, the similarity of their chemical processes, and the evidence of common ancestry. • Biological evolution accounts for the diversity of species developed through gradual processes over many generations. Species acquire many of their unique characteristics through biological adaptation, which involves the selection of naturally occurring variations in populations. Biological adaptations include changes in structures, behaviors or physiology that enhance survival and reproductive success in a particular environment.

Related Ideas From Benchmarks for Science Literacy (AAAS 1993) K–2: Evolution of Life

• Different plants and animals have external features that help them thrive in different kinds of places. • Some kinds of organisms that once lived on earth have completely disappeared, although they were something like others that are alive today.

K–2: Diversity of Life

• Some animals and plants are alike in the way they look and in the things they do, and others are very different from one another.

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K–2: Heredity

• There is variation among individuals of one kind within a population. • Offspring are very much, but not exactly, like their parents and like one another.

3–5: Diversity of Life

• A great variety of kinds of living things can be sorted into groups in many ways using various features to decide which things belong to which group.

3–5: Evolution of Life

• Individuals of the same kind differ in their characteristics, and sometimes the differences give individuals an advantage in surviving and reproducing.

3–5: Interdependence of Life

• Organisms interact with one another in various ways besides providing food. Many plants depend on animals for carrying their pollen to other plants or for dispensing their seeds.

3–5: Heredity

• Some likenesses between children and parents, such as eye color in human beings, or fruit or flower color in plants, are inherited. • For offspring to resemble their parents, there must be a reliable way to transfer information from one generation to the next.

6–8: Diversity of Life

• Animals and plants have a great variety of body plans and internal structures that contribute to their being able to make or find food and reproduce.

6–8: Heredity

• In some kinds of organisms, all the genes come from a single parent, whereas in organisms that have sexes, typically half of the genes come from each parent. • In sexual reproduction, a single specialized cell from a female merges with a specialized cell from a male. As the fertilized egg, carrying genetic information from each parent, multiplies to form the complete organism with about a trillion cells, the same genetic information is copied in each cell.

6–8: Evolution of Life

• Individual organisms with certain traits are more likely than others to survive and have offspring. Changes in environmental conditions can affect the survival of individual organisms and entire species.

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Chapter 7

Using the Story With Grades K–4

If you are interested in finding out what your students already think about plants, you might want to start by giving the probe “Is It a Plant?” from Uncovering Student Ideas in Science, Volume 2 (Keeley, Eberle, and Tugel 2007). It will give you valuable information on what kinds of organisms your students believe are plants and some insight into what they know about what attributes make something a plant. With young children you may have to read or put the plant names on a chart. Another way to do this probe with young children is to give them cards with pictures and names on them and have them sort them into “Plants” and “Not Plants” piles. Then they can tell you why they sorted the cards as they did. After this information is in your hands, you can create a “What I Know About Flowers” chart as a “Best Thinking Until Now” activity. After the children have listed the things they “know” about flowers, you can help them change their statements to questions that can be investigated. For example, children usually tell you that all flowers are pretty and smell good, or that bees and butterflies visit them. Some will say that butterflies or bees eat the flowers. At this grade level, children are seldom aware of the reproductive nature of flowers nor have they examined a flower closely. A good place to start is with asking the children to look at flowers carefully and to draw or list things they find that they have not seen before. You might also take this opportunity to introduce your class to the use of magnifying glasses. Show them how to hold the glass up to their eyes and bring the object to be viewed up to the glass until it is in focus. In a January 2004 article, “Discovering Flowers in a New Light,” in Science and Children, the authors suggest the use of digital microscopes to explore the parts of a flower (McNall and Bell). The article is well worth reading. You may be fortunate enough to have such devices in your school, but K–2 children are seldom adept at using them so a demonstration on a computer projection system may suffice. Young children can learn to use magnifying glasses with help, which is enough magnification to be useful in this activity. For the initial look at plants, a flower such as the Alstroemeria (commonly called the Peruvian lily), usually found in the supermarket floral section, is excellent. It is large and has ample floral parts for observation even with the naked eye. It is wise to ignore the Compositeae flowers such as dandelions, daisies, and sunflowers, because their tiny disk in the center of the rays of petals are not easily studied and can be confusing, particularly for younger students. I have found that observing objects for the purpose of drawing them is one of the best ways for students to focus on details. Ask the students if they have found parts of the flower they have not noticed before and if they have any idea what the parts are or what their purpose might be. I believe that it might well be enough for the students at the K–2 level to be aware of the floral parts and to find pollen on the anthers without learning the terminology of all floral parts. They should be able to learn that it is the pollen that moves with the help of insects to other flowers and has a part in developing the seeds that produce more flowers of the same

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kind. If your students are ready to go further, they can look at other flowers from a bouquet or their gardens and see if they can see similar parts in other flowers. Third and fourth graders should have no trouble labeling the drawings with your help on a poster or some other diagram. But before doing so and after they have examined the flower carefully and drawn it, you may ask them if they have any ideas what the purpose of the structures might be. It would be surprising if a few students did not have some ideas to share with the class. You might focus on structure and function here, asking if they notice anything about the structures that might give them a clue as to their function. If digital microscopes are available, the pollen will be very noticeable on the anthers and perhaps even on the tip of the stigma. Good detective work on the students’ part will develop some theories about what these parts might be for. They may be able to pull apart the ovaries and find the ovules, which are visible with good magnifiers but even more spectacular if you have a digital microscope. Asking them what they think these might be will get responses such as “seeds” or “pollen.” At this point, it would seem to be a good time to tell the students what botanists have discovered about the floral parts and ask the students to label their drawings using the poster or chart mentioned above. Their exploration beforehand will make your explanation even more effective because they have pondered over the mystery before you helped them to solve it. After this has been accomplished, it would be productive to ask them if they think other flowers have similar parts and to allow them to explore other flowers to see if they can compare and contrast the similarities and differences. With your knowledge from the Content Background section you should be able to help them use these comparisons and find other questions to be recorded in their notebooks for further discussion. There may be confusion if the students do try to decipher and use what they have learned while looking at flowers that do not follow exact placement of parts that they have dissected. Try to help them look at these “problem” flowers in an open way and assure them that regardless of where the parts are placed, the function and ultimate result is consistent. I think that at this age, the students should be responsible for knowing the basic principles of floral reproduction without a great deal of detail about genetics, although it is important for them to know variations in any individual can have an effect upon an entire population over time since that variation may be either successful or not and can affect an entire population. This, of course, is the basic principle of evolution.

USING THe STORY WITH GRADES 5–8 Much of the above kind of activities can be used in the higher grades especially

since students in these grades are capable of using optical or digital microscopes,— possibly more capable than we are at using the latter! I believe that dissection of the flowers is important at this level, and that knowing the reproductive parts and their function will help students understand the processes that go on in the

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Chapter 7

life cycle of a flowering plant. Drawing and labeling the plants in their science notebooks is essential. When students begin to ask questions about plants that are somewhat different than the simple ones they have dissected, you can help them see that all flowers have the same function (with the exception of flowers that are either pistillate or staminate). Some flowers, particularly the Compositeae are more difficult to fathom because they comprise many little flowers in the center of the “flower” and usually produce multiple fruits as, for example, the dandelion and the sunflower. If at all possible, I recommend that you work with the Wisconsin Fast Plants to allow your students to experiment with the life cycle of a plant and actually do the pollination of a flower and see the results. The fast plants are appropriately named because they go through their life cycles in approximately 40 days, seed to seed. They flower in about 14 days. You can get all the information you need to use these remarkable plants from the internet at www.fastplants.org. Children actually pollinate the plants by hand and can follow the life cycle of this plant right through to harvesting the next generation of seeds. The seeds and instructions can be purchased from the Carolina Biological Supply Company for between $10 and $25 depending upon how many seeds you need. You can grow them in a limited space since the plants are small and they grow under regular fluorescent light. Working with [fast plants] would be a logical extension of the explorations described above on flower anatomy and the understanding of the reproductive function of the flower. There are many investigations that can be carried out using the fast plants because the life cycle of 40 days allows for multiple experiments during a school year either for a whole class or for individuals. However, if this is not possible, watching and recording data from flowers in your area will provide a worthwhile activity as well. It takes a little patience, but one can watch bees and other insects or hummingbirds and observe how they feed in flowers that are compatible with their feeding style. Finding that bees and beetles actually enter the flower can be contrasted with the long proboscis feeding of the butterflies and moths and the hovering behavior of the long-beaked hummingbird and the sphinx moth. Students can find that the shape of the flower and the feeding habits of each animal are related by form and function of both feeders and plants. Hummingbirds and those insects with long beaks or long feeding tubes can suck nectar without entering the flower while the bees are required to enter into flowers, lacking extensions to their feeding mouth parts. The difference in shape of the flowers for each type of feeder should be emphasized through the concept of how form and function determine feeding habits. Students can also watch the flowers over a period of time in a garden setting and watch what happens as the flower falls to pieces and the ovary thickens to envelope the young seeds inside. Early blooming apple blossoms in the spring produce small fruits before the end of the school year. Many early blooming flowers do the same—the process can be drawn and noted, and the small fruits of some of the plants can be dissected to find the young seeds in the fruit. Crocuses, daffodils, irises, tulips, spring beauties, and many other early bloomers produce capsules at

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the base of the flower so that students can watch a flower and the development of the fruit and can dissect them easily. You could consider using two stories at once here if it is not too complicated. There is so much in common between this story and “Trees From Helicopters, Continued” that both could be used together, utilizing the flowers on the maple tree as examples of male and female flowers. The study of flowers and their functions and their relationships with the animals with which they have entered into partnerships should provide your students with an important overview of the importance of flowering plants and their role in our local and global ecosystems.

Related Books And Journal Articles Ashcroft, P. 2008. First explorations in flower anatomy. Science and Children 45

(8): 18–19. Driver, R., A. Squires, P. Rushworth, and V. Wood-Robinson. 1994. Making sense of secondary science: Research into children’s ideas. London and New York: Routledge-Falmer. Keeley, P. 2005. Science curriculum topic study: Bridging the gap between standards and practice. Thousand Oaks, CA: Corwin Press. Keeley, P., F. Eberle, and C. Dorsey. 2008. Uncovering student ideas in science: Another 25 formative assessment probes, volume 3. Arlington, VA: NSTA Press. Keeley, P., F. Eberle, and L. Farrin. 2005. Uncovering student ideas in science: 25 formative assessment probes, volume 1. Arlington, VA: NSTA Press. Keeley, P., F. Eberle, and J. Tugel. 2007. Uncovering student ideas in science: 25 more formative assessment probes, volume 2. Arlington, VA: NSTA Press. McNall, R. L., and R. L. Bell. 2004. Discovering flowers in a new light. Science and Children 41 (4): 35–39.

References American Association for the Advancement of Science (AAAS). 1993. Benchmarks for science literacy. New York: Oxford University Press. Keeley, P., F. Eberle, and J. Tugel. 2007. Uncovering student ideas in science: 25 more formative assessment probes, volume 2. Arlington, VA: NSTA Press. McNall, R. L., and R. L. Bell. 2004. Discovering flowers in a new light. Science and Children 41 (4): 35–39. National Research Council (NRC). 1996. National science education standards. Washington, DC: National Academies Press.

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Chapter 7

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Chapter 8

Looking at Lichens

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R

ick and Jeannie were walking through the woods one morning. Suddenly, Jeannie stopped in her tracks and said, “Rick, look at this tree! It has white bark. I don’t know of any trees that have completely snowwhite bark, except maybe a birch. But this isn’t a birch!” Rick took a closer look and exclaimed, “Wow! You’re right. This is no ordinary tree.” Now, Jeannie and Rick never took a walk in the woods without their magnifying glass and so they decided to look more closely at the strange tree with the white bark. “It looks like it is one big white scab,” said Rick, “and it completely covers the trunk of the tree.” “If you look at it closely, you can see that there are little bumps on it and some little black lines that look like they are raised above the surface!” Jeannie added, peering through the glass. “I wonder if we can peel it off and take some home for a better look under strong lights?” “Let’s try,” said Rick. “Oh, man, this stuff is stuck right to the bark of the tree and won’t come off unless we take some bark too.” “Well, I don’t think we will hurt the tree if we take just a little bark,” said Jeannie. And so they did. But the walk was not over and they began to see all sorts of interesting things growing on the trees. But they were not all alike! Some looked like little flowers but were green all over. Some looked like plants that had overlapping scales. Many resembled the white stuff they had spotted on the first tree, but were red, pink or yellow. Once they began to notice them, it seemed like they were everywhere. They were on leaves, rocks, and even on the ground! They took a lot of samples and found that some of the little green things came off the trees where they were growing without much, if any bark. The ones on the rocks would not come off easily at all and the same was true of the ones on the leaves. When they got home, they found some on the door of the woodshed. Now they began to see them almost everywhere. “Why haven’t we noticed them before, I wonder?” asked Rick. “Now that we have noticed them, it seems like we can’t find anything that doesn’t have some of them growing on it. Look, there is even some on the railing of this stair up to the house. I wonder what they are?” Jeannie and Rick knew Rebecca, a biologist at the local nature center and went to ask her. She looked at their samples and immediately said, “Those are lichens.” “Like-ums?” said Rick, “That’s a funny name, but we do like ’em.” “No, lichens,” said Rebecca. “L-I-C-H-E-N-S. They are very special kinds of organisms that are made up of two different kinds of living things. They live together, dependent on each other, in a way.” “How can we find out more about them?” the two young scientists asked together. “Well, I can help you some, but I think you can learn a lot just by looking at them under a microscope or a magnifying glass. You can keep on collecting them. Maybe drawing them will help too.” 

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PURPOSE Lichens are everywhere, yet most people fail to notice them because they are so famil-

iar. This story was written to help persuade teachers to acquaint their students with these unique forms of life. Many biology teachers, including myself, tend to gloss over the study of lichens and many of the other simple plants, even though lichens are universally available in virtually every environment, including urban centers. I hope that this story will help more students appreciate and become interested in them.

RELATED CONCEPTS • Fungi • Symbiosis • Reproduction

• Algae • Spores • Life cycles

DON’T BE SURPRISED Don’t be surprised if your students have never noticed or expressed interest in the lichens. Lichens are not usually flashy, although some of them have beautiful patterns and colors. Your students are probably not aware of the kind of relationship the fungi and the algae have. Older students will probably have some knowledge of plants or animals living together in some form of mutually dependent relationship (symbiosis) such as the bacteria and protozoa in the guts of termites. But the association between the fungi and algae in the lichens is an entirely unique relationship, well worth studying.

CONTENT BACKGROUND A lichen is a composite of a fungus and another organism that is capable of pro-

ducing food through photosynthesis. The latter may be green algae or cyanobacteria (blue-green algae) or sometimes both. When two organisms have a biological relationship, it is called symbiosis, and the partners are called symbionts. In lichens, the fungal part is called the mycobiont, and the algae the phytobiont or sometimes a photobiont. Lichens are named after the fungus partner since observing and classifying the algae is not practical because they are hidden within the thallus, or the body of the fungus. It was not until 1867 that anyone even thought that the lichen might be symbiotic, because the idea of two organisms living together as such was unheard of. It took until 1939 before the true nature of the lichen was proved and then accepted by the scientific community. You might find Lichens of North America (Brodo, Sharnoff, and Sharnoff 2001) of interest. Neither fungi nor the two types of algae are members of the plant kingdom, but each belong to their own: fungi in the kingdom Fungi, the cyanobacteria

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(blue-green algae) in the kingdom Monera, and the green algae in the kingdom Protista. Monerans are single-celled organisms that have no membrane around their nucleus. Protista is a kingdom that seems to encompass everything that doesn’t fit anywhere else, ranging from tiny protozoa to 30-meter-long kelp. It is important to realize that classification is somewhat arbitrary since it can change over time depending upon how the scientific community decides what traits define the organisms. The algae in lichens provide sugars for the fungi, while the fungi provide protection from ultraviolet (UV) light for the algae and some predators that could kill or damage them. The algae live between two or three layers of fungi, like the filling in a peanut butter and jelly sandwich, which is a good analogy for the lichen form (or morphology). The “bread” on top would correspond to what is called the upper cortex of the fungus layer, with closely packed fungal cells acting like skin. Beneath lies “jelly,” the fungal filaments called hyphae in which algae are embedded. These hyphae may grow small tubes that reach into algae to extract the sugars produced by the algae’s photosynthesis. Below that is the “peanut butter,” which corresponds to the medulla, a fungal layer that is not so densely packed as the outer layers, and where many of the living functions of the lichen occur. Finally, in most (but not all) lichens, is the bottom layer of “bread,” another tightly packed protective fungus layer called the lower cortex. This layer often contains structures that help the lichen attach to its host. Most fungi will combine with only one kind of algae but the algae are not as strict and may cohabitate with several different kinds of fungi. Something called morphogenesis happens when the lichen and algae “marry.” Neither organism is the same as it would be if it were found alone. Also, neither of the two organisms that make up lichen can be found living in isolation in the natural state. Only in the laboratory can the two be separated and examined as individuals. Even here, the resulting organisms are amorphous and fragile. Thus, each lichen is a totally unique organism, named, as stated before, for the fungal partner. Even though we were taught in school that lichens were the epitome of a mutualistic symbiosis, recent research has shown that few if any lichen species are equal partners in the symbiosis (Brodo, Sharnoff, and Sharnoff 2001). Mutualism occurs when two or more organisms interact in a way that is beneficial to all parties. You Diagram of the Lichen Structure Upper Cortex Algae Fungal Cells

Medulla

Hyphae (Fungus) Lower Cortex

Substrate (Rock, Bark etc.)

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and your students may immediately think of bees and flowers as examples. Flowers provide nectar for the bees that spread the pollen from flower to flower. Another example of mutualism is the protozoa that live in the gut of termites. The termites offer food and protection while the protozoa help to digest the cellulose (wood products) the termites ingest. The partnership in lichens ranges from mild parasitism by the fungi upon the algae to outright destructive behavior. Some fungi will actually kill their partner algae over time, but usually the photosynthetic partner will reproduce fast enough to keep ahead of the fungal aggressiveness. Lichenologist Trevor Goward described lichens as fungi that have “discovered agriculture” (Brodo, Sharnoff, and Sharnoff 2001, p. 4). In lichens, the photobiont (alga) can reproduce sexually or asexually (but mostly asexually). The mycobiont (fungi) reproduce by means of spores that can likewise be the result of sexual or asexual activity. When the windborne spores are produced asexually, they often carry some of the photobiont material with them. The spores resulting from sexual activity must find suitable algae with which they can combine in order to become viable. If you look closely, you can see the cuplike apothecia or long, dark, narrow ridges called lirellae across the surface. Both of these structures contain spores and are often used to identify the species of the lichen. Lichens can also undergo vegetative propagation by having pieces of the thallus break off and become windborne to another location. This way, alga and fungus are kept together. Lichens come in many forms and colors. Crustose (crustlike) lichens look as though they are glued to the bark of trees, leaves, or rocks. This is likely the form of lichen found by Rick and Jeannie covering the tree. It is impossible to take them off in their entirety without taking some of the substrate (like the bark). We Lichen Spore Structures Spores

Apothecia (or Lirella)

Substrate (Rock, Bark etc.)

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see only the upper parts of the thallus. The foliose (leafy) form of lichen is a little looser in its hold on the substrate, so we can lift and see both the upper and lower layers of the thallus. Squamulose (scalelike) forms show many overlapping parts of the thallus. The most dramatic lichen forms, the fruticose (shrubby) stand out from the substrate and may even look like moss or vines. One of these fruticose lichens is probably the most well known and misnamed, the so-called “reindeer moss,” which is really a lichen (Cladonia spp). Lichens are very difficult to identify to species levels. In order to distinguish one from another they often have to be keyed out by the chemicals that they produce. These metabolites, as they are called, can be recognized through various chemical tests and through a process called chromatography that separates out chemicals on either paper or gel by using a solvent. These chemicals can also glow in the presence of UV light. Each species of lichen has a distinctive color emission when you bathe it in UV light, which is yet another way of identifying the organism. Lichens know no bounds when it comes to climate or altitude. They range from sea level to mountaintops and from the tropics to the poles. They are found on any type of surface, including tree bark, leaves, plastic, rocks, soil, unwashed vehicles, and even on some insects.

Crustose form of lichen: Pertusaria xanthodes

Fruticose form of lichen: Ramalina complinata

Foliose form of lichen: Parmotrema cristiferum

Squamulose form of lichen (10×) Phyllopsera buettneri

(Thanks to Rick and Jean Seavey for original reference photos)

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Lichens provide food for many browsing animals and are capable of fixing nitrogen from the atmosphere into compounds useful by other organisms in the environment. They are also a “canary in the mine” in that they absorb pollutants and radioactivity so that their lack of health or even disappearance can be seen as a warning of polluted surroundings. One interesting characteristic of lichens is that they can endure long periods without water and become revived quickly once water is restored. Therefore they are very resilient to climate and weather changes. If you find dried-up looking lichen, you can douse it with water and within a few minutes see the color return. Despite the fact that they have been so often ignored, these organisms should invite a great deal of scrutiny because of their diversity and uniqueness, as well as their importance to the ecosystems of the world.

RELATED IDEAS from THE NATIONAL SCIENCE EDUCATION STANDARDS (NRC 1996) K–4: The Characteristics of Organisms

• Organisms have basic needs • Organisms can survive only in environments in which their needs can be met. The world has many different environments, and distinct environments support the life of different types of organisms.

K–4: Life Cycles of Organisms

• Many characteristics of an organism are inherited from the parents of the organism, but other characteristics result from an individual’s interaction with the environment.

K–4: Organisms and Environments

• An organism’s patterns of behavior are related to the nature of that organism’s environment, including the kinds and numbers of other organisms present, the availability of food and resources, and the physical characteristics of the environment. • All organisms cause changes in the environment where they live. Some of these changes are detrimental to the organism or other organisms, whereas others are beneficial.

5–8: Structure and Function in Living Systems

• Living systems at all levels or organization demonstrate the complementary nature of structure and function. Important levels of organization for structure and function include cells, organs, tissues, organ systems, whole organisms, and ecosystems.

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• All organisms are composed of cells—the fundamental unit of life. Most organisms are single cells; other organisms, including humans are multicellular. • Cells carry on the many functions needed to sustain life. They grow and divide, thereby producing more cells. This requires that they take in nutrients, which they use to provide energy for the work that cells do and to make the materials that a cell or an organism needs. • Specialized cells perform specialized functions in multicellular organisms. Groups of specialized cells cooperate to form a tissue, such as a muscle. Different tissues are in turn grouped together to form larger functional units, called organs. Each type of cell, tissue, and organ has a distinct structure and set of functions that serve the organism as a whole.

5–8: Reproduction and Heredity

• Reproduction is a characteristic of all living systems; because no individual organism lives forever, reproduction is essential to the continuation of every species. Some organisms reproduce asexually. Other organisms reproduce sexually.

5–8: Populations and Ecosystems

• A population consists of all individuals of a species that occur together at a given place and time. All populations living together and the physical factors with which they interact compose an ecosystem. • The number of organisms an ecosystem can support depends on the resources available and abiotic factors, such as quantity of light and water, range of temperatures, and soil composition. Given adequate biotic and abiotic resources and no disease or predators, populations (including humans) increase at rapid rates. Lack of resources and other factors, such as predation and climate, limit the growth of populations in specific niches in the ecosystem.

RELATED IDEAS from BENCHMARKS FOR SCIENCE LITERACY (AAAS 1993) K–2: Diversity of Life

• Some (organisms) are alike in the way they look and in the things they do, and others are very different from one another. • (Organisms) have features that help them live in different environments.

K–2: Interdependence of Life

• Living things are found almost everywhere in the world. There are somewhat different kinds in different places.

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3–5: Diversity of Life

• A great variety of kinds of living things can be sorted into groups in many ways using various features to decide which things belong to which group. • Features used for grouping depend on the purpose of the grouping.

3–5: Interdependence of Life

• Organisms interact with one another in various ways besides providing food.

6–8: Diversity of Life

• Similarities among organisms are found in internal anatomical features, which can be used to infer the degree of relatedness among organisms. In classifying organisms, biologists consider details of internal and external structures to be more important than behavior or general appearance.

6–8: Interdependence of Life

• Two types of organisms may interact with one another in several ways; they may be in a producer/consumer, predator/prey, or parasite/host relationship. Or one organism may scavenge or decompose another. Relationships may be competitive or mutually beneficial. Some species have become so adapted to each other that neither could survive without the other.

USING THE STORY WITH GRADES K–4 The best way to start this exploration is to go on a field trip to the backyard,

schoolyard, or anywhere there are trees, rocks, or objects upon which lichens grow. Take the trip yourself, first. If lichens are not available on school grounds, you can usually find them growing on tombstones in graveyards, particularly ones with limestone grave markers. Often, in older communities and even older schools, lichens readily grow on buildings. If you live in a mountainous region, the rocks will have lichens growing on them in abundance. Most children and adults will have seen lichens, but think that they are stains on the rocks and trees. Closer observation will show that many of the “stains” are really living lichens. Each child should have a magnifying glass and a notebook to draw in. Think about having a scavenger hunt, with teams of kids sent out to find and record the most lichens. For those lichens that can be taken back to the classroom, a digital projecting microscope can reveal the unique qualities of each. There are now digital microscopes on the market that allow you to save pictures to a computer. If your school has online capabilities, you can find many pictures of lichens on the internet through your search engine.

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Another activity involves the careful scraping of the top cortex from the lichen to reveal the green algae layer below. This can be accomplished only with careful dexterity and should probably be done by the teacher and shown to the students in the best way you have at your disposal (microscope, digital microscope, or hand lens). While looking for the lichens in the local environment your students can probably think of some interesting questions to investigate: • • • • • • • • • •

What is the most common color of lichens we have found? What kinds of shapes did the lichens exhibit? What kinds of trees do lichens seem to grow on most often? What kinds of trees do lichens seem to grow on least often? How many different colors did we find? Do they grow on any particular side (direction) of trees? Are there different kinds of lichens on the same tree or rock? What was the most common kind of lichen found? If animals were in or on the lichens, what kind were they? Within a set area, how many lichens were found and what kinds?

As you can see, there are many questions about the location, type, and physical attributes of lichens. Looking at lichens that are brought back to the classroom can provide some interesting observations too. Be careful, lichens grow slowly and can be damaged, so only bring home as many as you absolutely need. Drawings of the lichens plus information gathered on the field trip should be carefully recorded in their science notebooks.

USING THE STORY WITH GRADES 5–8 A field trip to the immediate neighborhood is in order for the middle school

group but you may wish to organize the trip differently than for younger students. Middle school students can set up an area where the lichens are most prevalent and then identify the trees where the most lichens are found. They might answer some of the same questions listed above and also add such questions as: • • • • •

What kinds of lichens are most prevalent on what types of bark? What types of bark are lacking lichens? Are colored lichens or plain lichens most often found on soil or on the rocks? Are there any lichens that seem to be trying to occupy the same space? What kind of lichens (crustose, foliose, squamulous, or fruticose) did they find?

If microscopes are available, have the students look at the lichens under low power and find the apothecia and lirallae if they are present. If the lichen is dry, have them place a few drops of water on the lichen thallus and then watch what happens as the water soaks in. Under microscopic view, they can scrape away a bit of the top of the thallus and get a view of the green layer containing the algae or

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cyanobacteria. They can also look for small organisms that might be lurking in the tangle of the lichen structure. This may be an eye-opening experience for most students and possibly for you as a teacher. Lichens are usually glossed over by most biology teachers, so this may be one of the few opportunities for your students to look at them closely. I can almost guarantee that once they are seen, they will hold your class’s interest.

RELATED BOOKS AND NSTA JOURNAL ARTICLES Keeley, P, 2005. Science curriculum topic study: Bridging the gap between standards

and practice. Thousand Oaks, CA: Corwin Press. Keeley, P., F. Eberle, and C. Dorsey. 2008. Uncovering student ideas in science, volume 3: Another 25 formative assessment probes. Arlington, VA: NSTA Press. Keeley, P., F. Eberle, and L. Farrin. 2005. Uncovering student ideas in science, volume 1: 25 formative assessment probes. Arlington, VA: NSTA Press. Keeley, P., F. Eberle, and J. Tugel.2007. Uncovering student ideas in science, volume 2: 25 more formative assessment probes. Arlington, VA: NSTA Press. Keeley, P., and J. Tugel. 2009. Uncovering student ideas in science, volume 4: 25 new formative assessment probes. Arlington, VA: NSTA Press. Konicek-Moran, R. 2008. Everyday science mysteries: Stories for inquiry-based science teaching. Arlington, VA: NSTA Press. Konicek-Moran, R. 2009. More everyday science mysteries: Stories for inquiry-based science teaching. Arlington, VA: NSTA Press. Konicek-Moran, R. 2010. Even more everyday science mysteries: Stories for inquirybased science teaching. Arlington, VA: NSTA Press.

REFERENCES Brodo, I. M., S. D. Sharnoff, and S. Sharnoff. 2001. Lichens of North America. New Haven: Yale University Press. Driver, R., A. Squires, P. Rushworth, and V. Wood-Robinson. 1994. Making sense of secondary science: Research into children’s ideas. London and New York: Routledge Falmer.

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Chapter 8

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Chapter 9

Seedlings in a Jar

S

ara and Ina were having an argument. Well, maybe not an argument; more like a disagreement about a science topic. Ina and Sara wanted to be scientists when they grew up. They had watched a science video about how a plant gets most of the stuff that makes up its stems and

leaves—what the scientists in the video called mass— from the air, as it grows. Sara wanted to know how this happened. She couldn’t believe that air could hold anything that could build a plant. She thought and thought about it, and the next day, she suggested to Ina that they try an experiment

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and grow a plant in a closed jar so that she could prove that plants didn’t get their mass from the air. “There isn’t enough air in this big pickle jar to make leaves and stems for a whole plant so if they grow, we know that the stuff that makes the plant comes from the soil or the water.” “Well, I’m not even sure we can grow plants in a jar, and not even sure we can sprout seeds in a jar with so little air,” said Ina. “That’s just the point,” Sara said. “If they need air to make them get bigger, they won’t grow in a jar. So if they do grow—which they won’t, I’m sure!—we can prove I am right.” “Okay, but I want to have some control over this experiment because I don’t think it will prove anything by just planting seeds in a closed jar,” said Ina. “I want to weigh everything we use so we can tell if anything is missing when it is over.” Ina had done scientific experiments before, and she knew about weighing ingredients and keeping track of them in her science notebook. “Fair enough,” said Sara. “It won’t make any difference anyway so if you want to go to all of the trouble of weighing everything, be my guest. Anyway I’ll bet the soil will weigh less, because that is where the plant gets its mass.” So they did weigh the jar and cover, the soil they put in, the water they added and, of course, the seeds they planted in the soil. Ina kept accurate records in her science notebook about everything they did. She even recorded the weight of the whole thing after it was put together and sealed up. Several weeks went by. The covered jar got very misty inside and, to their surprise, the seeds germinated and the seedlings grew up almost to the top of the jar. “There, you see!” said Sara. “The jar was closed as tight as can be, so no air leaked in or out and the plants grew just fine. The mass must have come from the soil or the water.” “Not so fast,” said Ina. “We have some weighing to do.” “What in the world for?” asked Sara. “We just proved that air had nothing to do with the seeds sprouting or the plants growing, didn’t we?” “Not to me we didn’t,” said Ina. “I want to weigh everything again.” “Suit yourself, Ina,” said Sara. “It’s a waste of time. It will weigh less because the soil and water got used up.” Sara and Ina weighed the whole set up and both said, “OMG!” Neither girl could believe their eyes. “Weigh it again,” said Sara. ‘There has to be something wrong!” Ina weighed the whole thing and got the same answer. Now neither girl knew what had happened. “Let’s weigh everything separately and see what it adds up to,” said Sara. They did and it all added up to the same number. They weighed the soil, which was wet with moisture, the jar, the lid, and the plants, which by now were quite large. “Okay, now what?” said Sara. “I think we really need to do this again,” said Ina.

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PURPOSE This story really leaves us hanging! It’s a great one for real investigation! There are

two purposes of the story: The first is to investigate closed systems. Anything that happens inside uses up only the materials in the jar, because there is no access to the outside world. The second purpose is for students to understand that air has mass and contains the materials that plants need to make their food and build their structure. I think a further purpose of the story is to allow the students to be puzzled by the outcome, and learn from this puzzlement how to try to find out how things happen.

RELATED CONCEPTS • Systems • Photosynthesis • Contents of the atmosphere

• Closed systems • Germination • Experimental design

DON’T BE SURPRISED Your students will probably be very surprised at the outcome of their investigation.

It would seem logical that the system would gain weight since the plants are growing inside the jar and they must weigh something! They are probably not aware of at least two things that are important, the implications of a closed system and the concept of air as having mass.

CONTENT BACKGROUND This story is about systems more than it is about seeds and plant growth, but you

will want some information about the latter, so I will provide that in this section. But first, let us look at the concept of systems. A system is a set of individual entities that interact and influence each other in the performance of a given task. The entities can be objects, people, internal organs, buses, plants, or dozens of other things that somehow interact in a meaningful way. The American Association for the Advancement of Science (AAAS 1993) believes the idea of systems to be one of the most important overarching concepts in learning and strongly urges educators to make the concept of systems a central part of all subjects taught in schools. After all, we are surrounded by systems, we live within systems and anything we teach or study is encased somehow in some system, somewhere. Students can apply the idea of systems to any topic and, most importantly, could see the relationships among the various topics they study. We so often complain that students do not see the big picture, but instead learn things in isolated

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Chapter 9

units and then fail to apply them across the curriculum. If systems were used as a unifying theme across all subjects, I believe that there would be more complete understanding of how everything in our everyday lives is related. In other words, they would see how the ideas involved in a transportation or political system related to how things work in an ecosystem or even a digestive system. Any change in any system affects everything else in that system. Systems are said to be closed or open. Actually there is a third type, an isolated system, but it has little importance here. A closed system such as the one in the story can exchange energy but not matter. The matter that is in the jar remains constant and cannot interact with the outside environment. However, sunlight can get through the glass and provide energy for photosynthesis. A hot liquid in a container, like coffee in a thermos, is another example of a closed system. Thermal energy can pass through the container walls so that eventually the hot liquid reaches equilibrium with its environment, but the coffee sealed inside can neither take in nor give out any of its substance. An open system allows both matter and energy to be exchanged with the environment. Our Earth is an example of an open system, where everything can react with everything else. Matter and energy are being exchanged all of the time. If the jar in the story had not been sealed off, it would have been classified as an open system since it could exchange matter and energy with anything outside the jar. With the idea of the seeds germinating and growing in what Sara considered an impossible growing environment, we add a different content twist to the concept of a closed system. Sara was under the influence of the popular misconception that air has no mass and therefore cannot possibly be part of the materials involved in the production of the plant tissues, or the mass, of growing plants. She believed that the plant mass comes from the soil and water, through the roots. She also believed that there was not enough air in the jar to grow anything. In the 1600s Jan Baptista Van Helmont planted a willow sapling in 200 pounds of soil, which after five years gained 164 pounds. (Obviously, he kept track of weights in his science notebook!). The soil lost only 57 grams of soil (2 ounces) during that time. Realizing that the loss in soil mass could not be responsible for the gigantic change in mass, he assumed it was the rainwater he had added that made up the difference in mass. Although he was aware of the carbon dioxide in the atmosphere, he could not believe that it could be responsible for the 164 pounds of additional weight. Here is an example of a misconception held by a scientist who did not have enough information to reach a conclusion that we now know is acceptable. This conclusion is that the carbon from the carbon dioxide in the air and water obtained through the roots can provide enough mass through photosynthesis to account for the gain in mass of the plants that grow on this Earth. The carbon and hydrogen in the presence of solar energy and chlorophyll are used to make sugars, which bond together to make starch and finally cellulose to form the cell walls of the cells from which plant tissues are made. By-products are newly formed water and oxygen, which are released into the atmosphere. Thus, the girls noticed the droplets of water on the jar’s inside surface, which showed

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that the water had condensed on the glass. There was enough carbon dioxide in the jar to provide the carbon necessary to allow plant growth. Since this was a closed system, mass was conserved since the only material available to the seed and subsequent plants was contained in the jar and the system should not gain any weight even though the appearance inside the jar changed considerably. Since the jar was transparent, solar energy could enter the system from the outside. Excess heat, if there was any could also be released through the glass and so energy could be exchanged. This permits us to use our definition of a closed system very well. The chemical formula that includes the formation of the new water molecules is 6 CO2 + 12 H2O + energy and chlorophyll → C6H12O6 + 6 O2 + 6 H2O Seeds need warmth and moisture in order to germinate. A few seeds, such as lettuce seeds also need light to activate the processes involved in germination. Some maple seeds can only last for a few weeks before they die if they do not germinate. Other seeds, such as the Lotus can remain viable for thousands of years. But it is the water and warmth that allow the seed to germinate. Water enters the seed, softens the seed coat and allows the chemical processes necessary for germination to proceed. Gibberellic acid is released and begins a series of rather complicated chemical and genetic steps that result in a dormant seed becoming a full-fledged plant. This plant is capable of producing more seeds so that the life cycle is completed. In the jar in the story, the girls provided the water and the growth medium, the soil. The room temperature and the Sun provided the warmth and that is all the seeds needed to germinate. The sunlight penetrating the glass jar walls provided the energy to cause the germinated seeds to grow into seedlings and then plants. As you may notice from the formula for photosynthesis, oxygen and water are also produced in the process and continue to provide necessary elements for plant growth. Plants need oxygen in order to respire (break down nutrients to produce useful energy) and water. The jar is a little microcosm of the outside world and might continue to exist for some time barring some changes inside that might inhibit the processes and stop the cycle. In the open system of the outside world, pests, disease, climate change, and a host of other problems may affect plants in the ecosystem. Yet, the open system of our Earth has survived for millions of years, changing in ways that have kept succession alive. We are now facing the prospects of what we humans have done to the ecosystem at large that may have dire consequences for living things on the planet.

RELATED IDEAS from THE NATIONAL SCIENCE EDUCATION STANDARDS (NRC 1996) K–12: Unifying Concepts and Processes—Systems

• The natural and designed world is now too large and complex to comprehend all at once. Scientists define small portions for the convenience of investigation. These portions are referred to as systems.

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Chapter 9

• A system is an organized group of related objects or components that form a whole. Systems have boundaries, components, resources, flow (input and output), and feedback. • Within systems, interactions between components occur. • Systems at different levels of organization can manifest different properties and functions. • Thinking in terms of simple systems encompasses subsystems as well as identifying the structure and function of systems, feedback and equilibrium and identifying the distinction between open and closed systems. • Understanding the regularities in systems can develop understanding of basic laws, theories, and models that explain the world.

K–4: The Characteristics of Organisms

• Organisms have basic needs. For example animals need air, water, and food; plants require air, water, nutrients and light. Organisms can survive only in environments in which their needs can be met. • The world has many different environments and distinct environments support the life of different types of organisms. • Each plant or animal has different structures that serve different functions in growth, survival, and reproduction.

K–4: Life Cycles of Organisms

• Plants and animals have life cycles that include being born, developing into adults, reproducing, and eventually dying. The details of this life cycle are different for different organisms. • Plants and animals closely resemble their parents.

5–8: Structure and Function in Living Systems

• Living systems at all levels of organization demonstrate the complementary nature of structure and function. Important levels of organization for structure and function include cells, organs, tissues, organ systems, whole organisms, and ecosystems.

5–8: Reproduction and Heredity

• Reproduction is a characteristic of all living systems because no individual organism lives forever. Reproduction is essential to the continuation of every species. Some organisms reproduce asexually. Other organisms reproduce sexually.

5–8: Diversity and Adaptations of Organisms

• Millions of species of animals, plants, and microorganisms are alive today. Although different species might look dissimilar, the unit, among organisms becomes apparent from an analysis of internal structures, the similarity of their chemical processes and the evidence of common ancestry.

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RELATED IDEAS FROM BENCHMARKS FOR SCIENCE LITERACY (AAAS 1993)

Chapter 9

K–2: Systems

• Most things are made of parts. • Something may not work if some of the parts are missing. • When parts are put together, they can do things that they couldn’t do by themselves.

3–5: Systems

• In something that consists of many parts, the parts usually influence one another.

6–8: Systems

• A system can include processes as well as things. • Thinking about things as systems means looking for how every part relates to others. The output from one part of a system (which can include material energy or information) can become the input to other parts. Such feedback can serve to control what goes on in the system as a whole. • Any system is usually connected to other systems, both internally and externally. Thus a system may be thought of as containing subsystems and as being a subsystem of a larger system. • Some portion of the output of a system may be fed back to the system’s input. • Systems are defined by placing boundaries around collections of interrelated things to make them easier to study. Regardless of where the boundaries are placed, a system still interacts with its surrounding environment. Therefore, when studying a system, it is important to keep track of what enters or leaves the system.

K–2: Diversity of Life

• Some animals and plants are alike in the way they look and in the things they do, and others are very different from one another. • Plants and animals have features that help them live in different environments.

K–2: The Structure of Matter

• Things can be done to materials to change some of their properties, but not all materials respond the same way to what is done to them.

3–5: Diversity of Life

• A great variety of kinds of living things can be sorted into groups in many ways using various features to decide which things belong in which group.

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• Features used for grouping depend on the purpose of the grouping.

6–8: Diversity of Life

• Animals and plants have a great variety of body plans and internal structures that contribute to their being able to make or find food and reproduce. • For sexually reproducing organisms, a species comprises all organisms that can mate with one another to produce fertile offspring.

USING THE STORY WITH GRADES K–4 Young children can examine their toys and things that they build or use to iden-

tify the parts that make up what we call systems. According to the standards, they should realize that toys are made of parts and that if some parts are missing, the toy does not work correctly. This can be an important introduction to the concept of systems. A bicycle cannot operate without a wheel and an electronic toy cannot operate without a source of power such as batteries or a wind-up spring. Looking at toys and identifying their parts can also be instructive for children as they develop the idea of systems. It is important that young children begin their understanding of systems by realizing that the parts of systems interact with each other in ways that make the system work properly. When I was a young boy, I became enamored with locks and to my parents’ chagrin I managed to take apart most of the locks on the doors of our house. It seemed like I always had parts left over when I reassembled them. Of course they didn’t work and we had to start all over again. But in doing so, I learned more about how locks work than I would have in any other way. I wanted to believe that it made no difference if one little part was left out of the lock system. But, of course, it did. Helping children to see that successful systems have to consist of all of their parts is one of the most important things they can learn. The application of this idea to the larger examples of systems in the world will prove invaluable. You might try giving the probe “Is it a system?” from Uncovering Student Ideas in Science, Volume 4 (Keeley and Tugel 2009). This probe will provide you with more information about your students’ knowledge about systems. Students are asked to choose from a list, those things that they think are systems, and then explain their reasoning. In all of these activities, the important thing is the discussion that follows. A teacher learns more about how and what their students learn by listening than by talking. You may hear students holding opposite points of view and not even realizing it. With careful probing you can help them to see what they are saying is in conflict. I once had a student who was in the middle of an explanation and stopped and said, “now that I heard what I just said, I can see that I am heading in the wrong direction.” Hearing oneself speak out loud is often a better key to understanding what we are thinking than just pondering it silently. Additionally, writing it or drawing it can also add information that aids in

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understanding, especially, if one is writing for oneself as the audience. The writer can be more honest that way. Your students may want to try the activity in the story. Young children may not be ready to use the skills necessary to carry out the activity. Older elementary students who can use a balance or scale and follow the story line carefully can repeat the activity and after predicting the outcome, can find the seemingly amazing outcome for themselves. They may want to see how long the microcosm in the jar will perpetuate itself. If you help them to use plants that will not grow too tall too quickly, the chances are that it might go on for some time.

USING THE STORY WITH GRADES 5–8 Middle school children will be just as surprised as the younger students with the

results and you might be too. Don’t be surprised if you expected the jar of plants to weigh more. It almost seems counterintuitive that the plants could grow from the seeds and still not add any weight to the system. This particular system however, is the secret to the result. Try to focus on the system being closed and appeal to their knowledge that nothing in and nothing out yields no changes. The inspiration for the story came from the probe, “Seedlings in a Jar,” in Keeley and Tugel’s book (2009). Although giving this probe may seem redundant since it follows the story so closely, it could be used as a summative assessment. You would need to pay closer attention to the part of the probe where the students are required to elucidate in their own words why the system did not gain weight. When the students decide to replicate the story, you may want to talk with them about systems and have them find as many different kinds of systems that they can think of in their collective experiences. This particular moment in the process is the best time to introduce the vocabulary since the words will be in context. Older students, being more facile with balances, will want to weigh the substances before and after, and check the results several times. I have found that their disbelief based on prior conceptions, is strong and sometimes hard to shake. Prior conceptions held for a long time are difficult to change with one activity no matter how strong the evidence may seem to us. If you do not get all of your students to understand the concepts involved here, do not be discouraged. Instead, congratulate yourself on having built one more plank in the scaffolding that leads to final understanding. Believing that the air in the jar was sufficient to contain the building blocks of the plant tissue is completely ridiculous to students who believe that air has no mass. If you are planning to follow up this story with photosynthesis, I believe that you will find the students more receptive to the ideas involved because they have actually seen results that point to the carbon dioxide in the air as the source of carbon that will be the backbone of the starch and sugar molecules and eventually the cellulose. If you would like to see an interview of a young student by an interviewer who uncovers his lack of understanding about photosynthesis, log onto the following: www.learner.org/resources/series26.html and watch the video “Lessons From Thin

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Chapter 9

Air.” It will give you an idea how difficult it is to change student conceptions about air and mass.

RELATED BOOKS AND NSTA JOURNAL ARTICLES Keeley, P. 2005. Science curriculum topic study: Bridging the gap between standards

and practice. Thousand Oaks, CA: Corwin Press. Keeley, P., F. Eberle, and C. Dorsey. 2008. Uncovering student ideas in science, volume 3: Another 25 formative assessment probes. Arlington, VA: NSTA Press. Keeley, P., F. Eberle, and L. Farrin. 2005. Uncovering student ideas in science, volume 1: 25 formative assessment probes. Arlington, VA: NSTA Press. Keeley, P., F. Eberle, and J. Tugel. 2007. Uncovering student ideas in science, volume 2: 25 more formative assessment probes. Arlington, VA: NSTA Press. Keeley, P., and J. Tugel. 2009. Uncovering student ideas in science, volume 4: 25 new formative assessment probes. Arlington, VA: NSTA Press. Konicek-Moran, R. 2008. Everyday Science Mysteries: Stories for inquiry-based science teaching. Arlington, VA: NSTA Press. Konicek-Moran, R. 2009. More everyday science mysteries: Stories for inquiry-based science teaching. Arlington, VA: NSTA Press. Konicek-Moran, R. 2010. Even More Everyday Science Mysteries: Stories for inquirybased science teaching. Arlington, VA: NSTA Press.

REFERENCES Annenberg Media. 2009. Lessons from thin air. Minds of Our Own. www.learner. org/resources/series26.html Keeley, P., and J. Tugel. 2009. Uncovering student ideas in science: 25 formative assessment probes, Volume 4. Arlington, VA: NSTA Press.

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Chapter 10

Seed Bargains

J

immy and Jeanine were twins. Not that you could really tell by looking at them. Jimmy was blond and blue eyed while Jeanine is dark haired and dark eyed. But they were twins, born about one minute apart. Jeanine was the first one born and she never let Jimmy forget that she is his “older” sister. They were both in the third grade and in the same class, Mr. Scott’s class, and they both thought he was cool. In

fact, they thought that third grade was cool. They could read well and Mr. Scott let the class do special projects by themselves because he said they were “mature” kids. Mr. Scott had started a unit on plants and Jimmy and his partner George had chosen to do something with seeds. Jimmy was elected to get the seeds for the project and got his mom to drive him to the Pioneer Valley Garden Center to get some “good ones.” Jeanine

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went along for the ride after school because she wanted to get some catnip for their cat. Jimmy went to the display where the seeds were located and found some blackeyed peas that looked interesting. “I’ll take these,” said Jimmy to his mom. “There are about fifty of them so that should be plenty for any experiments George and I want to do.” “Looks good to me,” said Mom, “and they are only $3.99.” They bought the seeds and Jimmy looked at the brightly colored package with the picture of the beans looking healthy and green. “I hope our plants look like these.” Jeanine got Mom to pay for the catnip plant for her pet and they left the garden center and got into the car. “I’ve got to stop at the supermarket to get something for supper,” said Mother. “Do you want to come in?” Both children decided to join her in hopes that they might be able to talk Mom into getting some ice cream as well. Soon they were following her up the aisles as she did her shopping. Suddenly, Jeanine yanked on Jimmy’s collar as he went by and said, “Hey little brother, look at this. Here are your beans without the fancy package.” Jimmy stopped and looked at the package of black-eyed peas Jeanine held in her hands. They looked the same but the package was much bigger. “That’s more than we need,” he said. “What did you pay for yours?” asked Jeanine. “$3.99 plus tax,” answered Jimmy. “Well,” said Jeanine, “This looks like twice as many and they are only 99 cents.” “One pound,” read Jeanine from the package. “Why didn’t you get these instead? “I don’t know,” he answered. “Wait until I ask Mom.” “I guess these are cheaper for a reason,” said Mom after the two children had asked her their question. “But, I don’t know what that reason is. Let’s buy this package for 99 cents and go back to the garden center and ask them.” A quick drive brought them back to the garden center and within seconds Jimmy was asking the clerk why there was such a price difference in the two packages. “Well,” said the clerk, “I think that the ones we sell are probably better because they’re raised specifically for planting. The others are raised for food. Otherwise, we wouldn’t charge that much more. Ours must be better.” “What kind of better?” said Jimmy. “Will yours grow faster or what? How do you know they’re better?” The clerk asked some other folks from the garden center but all he got in return was that everybody thought that the garden center’s seeds were “better.” “Gee, we’re not even sure what better means,” said Jeanine. “I’ll bet I could figure how to find out though.” “Yeah,” said Jimmy, “maybe George and I can figure out a way to test these seeds. And that could be a neat science project!”

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Purpose Children as well as adults are usually intrigued by the ideas of bargains. More seeds

for less money is often enough to convince them to buy a larger, cheaper package. In this case, the children are savvy enough to question the value of either package. One seems overly expensive and the other too good to be true. Another common response among consumers of any age is that the more something costs, the better it must be. Implicit in this story is the question, “Which package is the best value?” This story presents a case and an opportunity for promoting the development of alert skepticism as young consumers. This attitude is also important in developing good science habits. It differs from cynicism in that cynicism usually expects fraud or the negative side of any argument to be dominant. Alert skepticism merely suggests that each argument be carefully weighed and that data support any position. In the case of the seeds, the children in the story ask the right questions: “Why is there such a difference in the prices of the two packages?” and “What are the differences between the two kinds of seeds, if any?” Implied is the question to the garden center salesperson, “Why do you charge more for your seeds?” And finally, “What do you mean by better and can you tell me specifically what better means?” The story then suggests that the children can find out for themselves what differences, if any, there are between the two groups of seeds. In addition, it asks the children to decide what “better” might mean. It becomes their task to create the criteria upon which they will design their investigations and their predictions.

Related Concepts • Germination • Plants • Life cycles and seeds

• Living things • Needs of living things • Experimental design

Don’t Be Surprised Although planting seeds and seeing plants as a result is a common experience for children, they still have a problem seeing seeds as a plant, complete with food enclosed in the package for giving the seed nutrition until it germinates and begins producing its own food. They often benefit greatly from “looking inside” a wellsoaked lima bean and seeing the embryo of the bean plant. Since the story focuses on experimental design, you may be surprised how meticulous your students will be in order to design a fair test for their plants. Since they have yet to decide what they mean by “better,” they may need help in looking at variables in plants as they grow and be reminded of the importance of the germination ratio.

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Chapter 10

Content Background

Seeds that are harvested strictly for planting are usually chosen for their viability and are grown for the purpose of planting in gardens or farms. Commercial seed producers avoid any chance of cross-pollination by isolating different varieties of plants and hand pollinating them. Sometimes they are kept away from pollinating insects under nets or in greenhouses. They also keep them away from different types of plants by keeping them at least a mile away from other types of plants, beyond the distance that the average bees fly. Seeds harvested for food are harvested in bulk and are not expected to give genetically pure offspring if planted. Seeds raised for planting are bred for their resistance to disease and hardiness to inclement weather. Their genetics are closely controlled, so that there is very little, if any, variation among the seeds and the resulting plants. Besides these opportunities to learn more about asking good questions and designing and carrying out investigations, there are a great many opportunities to learn about the germination of seeds, the growth of seedlings, and the conditions for growth. In addition, there are many questions that can arise concerning the planting of seeds and the growth patterns of the seedlings as they mature. Results may differ. Sometimes, the germination rate of the grocery beans is low; sometimes there is no difference between seed types. Sometimes, there are many broken beans in the grocery package and sometimes very few. This means that you are really experiencing inquiry since the outcome for your class may be unique. It is also difficult to find secondhand information about this topic so the students’ data are original and there are no set expectations to guide their work. You can also be involved since you do not have a hidden agenda for final conclusions except for the design of the investigation. The cotyledon(s) are the first leaves to be seen as the plant breaks the surface. These are also called seed leaves and begin the photosynthesis process for the young plant. Seeds also include a substance called endosperm, which provides nutrition to help the plants begin their germination. Plants are known as producers since they are the only living organisms that produce food from the carbon dioxide in the air with the energy from the Sun and the help of a substance called chlorophyll. Animals that eat plants and each other are known as consumers. Almost all of the energy that exists in the world can trace its origin back to the Sun and sunlight’s interaction with green plants.

Related Ideas From the National Science Education Standards (NRC 1996) K–4: The Characteristics of Organisms

• Organisms have basic needs. For example, plants require air, water, nutrients

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and light. • Each plant or animal has different structures that serve different functions in growth, survival, and reproduction.

K–4: Life Cycles of Organisms

• Plants and animals have life cycles that include being born, developing into adults, reproducing, and eventually dying. The details of this life cycle are different for different organisms. • Plants and animals closely resemble their parents.

5–8: Life Cycles of Organisms

• All organisms must be able to obtain and use resources, grow, reproduce and maintain stable internal conditions while living in a constantly changing external environment.

Related Ideas From Benchmarks for Science Literacy (AAAS 1993) K–2: Cells

• Most living things need water, food, and air.

K–2: Flow of Matter and Energy

• Plants and animals both need to take in water, and animals need to take in food. In addition, plants need light.

K–2: Agriculture

• Most food comes from farms either directly as crops or as animals that eat the crops. To grow well, plants need enough warmth, light, and water.

3–5: Flow of Matter and Energy

• Some source of energy is needed for all organisms to stay alive and grow.

3–5: Agriculture

• Some plant varieties and animal breeds have more desirable characteristics than others, but some may be more difficult or costly to grow.

6–8: Flow of Matter and Energy

• Food provides the fuel and building material for all organisms. Plants use the energy from light to make sugars from carbon dioxide and water. This food can be used immediately or stored for later use.

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Chapter 10

6–8: Agriculture

• People control the characteristics of plants and animals they raise by selective breeding and preserving varieties of seeds (old and new) to use if growing conditions change.

Using the Story With Grades K–4 A good way to start is by giving the probe “Needs of Seeds” from Uncovering

Student Ideas in Science, volume 2 (Keeley, Eberle, and Tugel 2007). This will provide you with valuable information about what kinds of prior conceptions your students bring to class. When we have used this story with children in a classroom, we usually have the two packages of seeds to show the class. In addition, we have milk cartons, cups or other containers, and potting soil for the upcoming experiments on hand. It is important that the containers be the same shape, composition, and size. It is just as important that the potting soil be the same brand if more than one bag is used. If you want to create a situation where the children have to argue about controlling variables, have some materials that are different in some ways. In this way, the students will have the opportunity to discuss with their peers the importance of controlling variables in experiments. Once these discussions have occurred, it is usually enough to heighten their awareness for controlling other variables. If they forget some, a few well-placed questions about a variable will help them to remember. The third- and fourth-grade students we have worked with immediately saw the potential for the experiment. It is, in essence, an opportunity to pit one group of seeds against another—a race or a contest. But it must be fair and children, who play games, know at an early age what “fair” means. You can help them to see that “fairness” is important in this contest as well as in their games. No seed or group of seeds should have an unfair advantage over the others. Thus, you may be overwhelmed by demands that all materials and conditions be exactly the same. This shows that they are taking the investigation seriously. There are many questions that will come up or perhaps will need you to point out. For example, the seed packet will suggest appropriate depths for planting the seeds. What happens if you plant them deeper? Shallower? Upside down? Is there an up and down position? Sometimes these can be tested in a plastic bag garden. Directions describing the plastic bag seed germination setup can be found at www.iit.edu/~smile/bi9404.html. There are any numbers of variables available to you in using this technique. For a great article about seventh graders learning about plants and seeds see Donna West’s article “Bean Plants: A Growth Experience,” in the April 2004 issue of Science Scope. Even though it is about seventh graders, it has much to offer teachers of any grade level.

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You can expect some obvious differences in the results of this activity using the two kinds of seeds. Seeds found in the stores destined for soups and stews are often broken and treated harshly in harvest and packaging. Your students will find many seeds without coats or that are damaged and unusable. The students will have their first decision to make about choosing seeds from the less expensive package that appear to be most healthy. But, at the same time it will raise the question about which is the “best buy.” Were all of the seeds in the planting package in good shape? What was the ratio of usable seeds from one package to the other? Then, what will be the germination rate? Will one set of seeds germinate first? This latter question will have to be decided by making an operational definition. For example, the question arises, “When do we say the new plant has emerged? When the dirt parts to make way for the plant? When the first green stalk is seen?” These definitions are necessary if group data are to be compiled. Other questions may be: “Does the germination time make a difference in how good a seed is?” and “How long do we wait to see if the seed is viable before we dig down and see?” When the seeds have broken the surface, if they are, for exemple, legumes, they will have two seed leaves, or cotyledons, visible. What are they and what do they do? What happens to them as the plant grows? Were they inside the seeds before they were planted? Ask your students if they can find a way to look inside the seed, or you can suggest that the students soak some seeds and dissect them to see what is inside. As you can see, these types of questions can be answered through second-hand inquiry as well as a result of firsthand inquiry. The plants can be measured for rate of growth. They can be rated on their looks as spindly or healthy. Which are the first to flower? Each day of observation will bring new questions. These observations and questions should all be recorded in their science notebooks and posted on a poster page, prominently displayed and discussed in scientific discourse. Finally, it may well be that there will be little if any differences among the plants. The conclusion might be that for science projects, the store seeds are just as good as the expensive ones. Often in consumer related tests, comparisons of different brands of paper towels, popcorn, window cleaners, and other products, the advertising hype turns out to be just that—hype. Still, it is a finding and is supported by experimental results.

Using the Story With Grades 5–8 You may also want to start by giving the probe “Needs of Seeds” from Uncovering Student Ideas in Science, volume 2 (Keeley, Eberle, and Tugel 2007). It will let you know a great deal about what your students think about seeds and what seeds need to germinate. Most of the information given in the section for grades K–4 above will be of value to middle school teachers. I especially recommend the Donna West article mentioned on page 106 for great ideas for following up on the initial inquiries with the seeds. At this level you will want to focus on the parts of the plants as

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Chapter 10

they continue to grow and look at the kinds of media in which the plants grow, the amount of light, and the adaptations of plants to their environment. Here also you may begin to introduce your students to the miracle of photosynthesis. I can also recommend viewing the Annenberg channel for an enlightening interview with a student about photosynthesis. It is a must see for teachers who are going to teach about photosynthesis. The address is www.learner.org/resources/series29.html. Scroll down and select Workshop 2 for the photosynthesis video. You will have to register on the channel first but this is free. Incidentally, there are many interesting videos on this site on all topics. These videos are among some of the best aids to teachers on misconceptions and inquiry teaching.

Related Books and Journal Articles Driver, R., A. Squires, P. Rushworth, and V. Wood-Robinson. 1994. Making sense

of secondary science: Research into children’s ideas. London and New York: Routledge Falmer. Keeley, P. 2005. Science curriculum topic study: Bridging the gap between standards and practice. Thousand Oaks, CA: Corwin Press. Keeley, P., F. Eberle, and L. Farrin. 2005. Uncovering student ideas in science: 25 formative assessment probes, volume 1. Arlington, VA: NSTA Press. Keeley, P., F. Eberle, and J. Tugel. 2007. Uncovering student ideas in science: 25 more formative assessment probes, volume 2. Arlington, VA: NSTA Press. West, D. 2004. Bean plants: A growth experience. Science Scope 27 (7): 44–47.

References American Association for the Advancement of Science (AAAS). 1993. Benchmarks for science literacy. New York: Oxford University Press. Annenberg Foundation. Photosynthesis video. www.learner.org/resources/series29. html. Keeley, P., F. Eberle, and J. Tugel. 2007. Uncovering student ideas in science: 25 more formative assessment probes, volume 2. Arlington, VA: NSTA Press. National Research Council (NRC). 1996. National science education standards. Washington, DC: National Academies Press. West, D. 2004. Bean plants: A growth experience. Science Scope 27 (7): 44–47.

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Chapter 11

Springtime in the Greenhouse

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I

t was springtime again. Eddie and Kerry were back hanging out with their mother in the now year-old greenhouse. Mom is a master gardener, and she loved to plant seeds for their vegetable and flower gardens. Even though it was still cool outdoors, the cozy daytime warmth within the greenhouse made it possible for Mom to plant seeds to transplant into their own garden, as well as into her customers’ gardens. She could wait and buy ready-to-go plants at the nursery, but that just added to the cost. Growing plants “from scratch” allowed Mom to make a little profit in her gardening business. The greenhouse was unheated except for sunshine during the day, so at night, it cooled off. So Mom had bought a big electric heating pad, which provided nighttime warmth to seed trays placed upon it. The three of them were standing in the greenhouse with packets of seeds, planting trays, soil, water, and fertilizer. “Hey,” said Mom, “do you want to help me to plant our new crop for the year?” “Sure,” said the kids, who loved watching the little seedlings emerge from the soil. “But what do we need to do to make these seeds sprout?” Mom liked to help them with vocabulary, so she told them that a more correct word for sprouting was germinating. “What do you kids think we should put in the planters along with the seeds so that they germinate and start their new lives strong and healthy?” she asked. “Well, soil for sure, and fertilizer seems to be important for plants to grow, so I guess fertilizer would be good,” said Kerry. “But I’m not sure it is necessary since I heard that the seed has everything it needs to spr…er, germinate right inside.” “I’m pretty sure that we need sunshine to help them germinate, but how does it get down to the seed when it’s under the soil?” asked Eddy. “Good question,” said Mom. “Maybe it is just the sunshine on the top of the soil that does the trick,” said Kerry. “But I’m sure they need water.” “Why do you think that?” asked Eddy. “Well, we did a lot of stuff with seeds at school and we always had to soak them first or they wouldn’t open up so we could look at what was inside.” “Okay … that sounds right. But don’t they need to be kept warm all of the time?” asked Kerry. “I sorta think so.” “Well, the greenhouse does that during the day and the heating pad will do that at night,” said Eddy. “Hmm. I guess we have some questions to answer here,” said Mom. “How do you think we can set up a little experiment to find out what seeds need and don’t need to germinate?”

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PURPOSE Children are often under the impression that fertilizer is necessary for the health of

plants just as vitamins are for people and animals. However, seeds and plants are entirely different things. It’s important to help them realize that most seeds come equipped with all the nutrients they need to germinate and basically only require warmth, oxygen, and moisture to begin growth.

RELATED CONCEPTS • Nutrition • Life cycles

• Germination • Photosynthesis

DON’T BE SURPRISED Children and adults alike are prone to believe that if a little of something is good, more

is better. In the case of this story, your students will probably believe that if fertilizer is good for growing plants, it must be good for germinating seeds. This may come from seeing gardeners plant seeds in fertilized beds, which is a way of making sure that the germinated seeds will have a fertile substrate in which to grow, but has nothing to do with the seeds’ ability to germinate. You may be surprised yourself that some seeds need light for germination, a theory that is being verified through new research.

CONTENT BACKGROUND Seeds are little packages of “ready-to-go plants.” They come with a protective coat-

ing, food for their first meals and the ability to break open their seed coat and begin life. If they are healthy, they are definitely alive. Many people do not consider them so because they appear dead or unmoving, like rocks, but they have all the characteristics of a living organism. All the while they are waiting to be planted, they are respiring and using the stored food (endosperm) until that time that conditions are right for them to germinate. Seeds need at least three things to make this happen: moisture, oxygen, and warmth. Taking in moisture (imbibition) will help them to soften the seed coat and swell the cells inside the seed, to begin the growth processes directed by the plant’s genetic instructions. They need oxygen for cell respiration, like all living things. These processes are facilitated within warmer, rather than colder temperature ranges. Until these conditions are met, the seed stays dormant. There are some seeds that also need light in order to germinate, but they are the exception instead of the rule. In some lettuce and barley seeds, light is needed to stimulate the action of gibberellic acid, which sets a complex set of biochemical steps in motion to help the seeds germinate.

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Chapter 11

Water enters the seed usually through the opening called the hilum, where the seed was attached to the wall of the ovary. The process called imbibition swells the seed and breaks down the seed coat, allowing the seed to make connection with its surrounding environment. Water also helps to release the enzymes necessary to break down the stored food (endosperm) into usable components of oils, starches, and proteins. This food will help the seed to maintain its life until it has released several parts of the embryonic seed (the primitive forms of root, stem, and leaves) that will eventually make it a free-living, photosynthetic organism. All this time, the seed needs to carry out cellular respiration to consume its stored food supply. This means that the embryo uses oxygen to burn the food and use the by-products. When the seed’s protective coat is broken, the seed gains access to this element in the soil. During germination, the radical, or primitive root, emerges, followed shortly by the hypocotyl, the primitive stem upon which are found the cotyledons, the “seed leaves” that will begin the first photosynthetic processes so that the new seedling can carry on its own metabolism. All of the above parts are present in an embryonic form in the seed before it has germinated. Soon after germination and the establishment of the seedling, the cotyledons will fall off and the new leaves will take over as the plant grows to its fullest potential. For a wonderful little animation of a germinating seed, go to www.botanical-online.com/animation4.htm. You may find other animations by searching the internet for “seed germination animation.” After the germination of the seed is complete, the new plant will certainly benefit from the fertilizer in the soil, but that was not the question asked in the story. Mom explicitly asked what the seed needs to germinate. I believe that your students will know all there is to know in order to carry out the investigation to see what seeds need or don’t need in order to germinate.

RELATED IDEAS FROM THE NATIONAL SCIENCE EDUCATION STANDARDS (NRC 1996) K–4: Abilities Necessary to Do Scientific Inquiry • • • • •

Ask a question about objects, organisms, and events in the environment. Plan and conduct a simple investigation. Employ simple equipment and tools to gather data and extend the senses. Use data to construct a reasonable explanation. Communicate investigations and explanations.

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K–4: The Characteristics of Organisms

• Organisms have basic needs. For example, animals need air, water, and food; plants require air, water, nutrients and light. Organisms can survive only in environments in which their needs can be met. • The world has many different environments and distinct environments support the life of different types of organisms. • Each plant or animal has different structures that serve different functions in growth, survival, and reproduction.

K–4: Life Cycles of Organisms

• Plants and animals have life cycles that include being born, developing into adults, reproducing, and eventually dying. The details of this life cycle are different for different organisms. • Plants and animals closely resemble their parents.

5–8: Abilities Necessary to Do Scientific Inquiry • • • •

Identify questions that can be answered through scientific investigations. Design and conduct a scientific investigation. Use appropriate tools and techniques to gather, analyze, and interpret data. Think critically and logically to make the relationships between evidence and explanations.

5–8: Structure and Function in Living Systems

• Living systems at all levels of organization demonstrate the complementary nature of structure and function. Important levels of organization for structure and function include cells, organs, tissues, organ systems, whole organisms, and ecosystems.

5–8: Reproduction and Heredity

• Reproduction is a characteristic of all living systems because no individual organism lives forever. Reproduction is essential to the continuation of every species. Some organisms reproduce asexually. Other organisms reproduce sexually.

5–8: Diversity and Adaptations of Organisms

• Millions of species of animals, plants, and microorganisms are alive today. Although different species might look dissimilar, the unity among organisms becomes apparent from an analysis of internal structures, the similarity of their chemical processes, and the evidence of common ancestry.

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RELATED IDEAS FROM BENCHMARKS FOR SCIENCE LITERACY (AAAS 1993) K–2: Scientific Inquiry

• People can often learn about things around them by just observing those things carefully, but sometimes they can learn more by doing something to the things and noting what happens. • Describing things as accurately as possible is important in science because it enables people to compare observations with those of others. • When people give different descriptions of the same thing, it is usually a good idea to make some fresh observations instead of just arguing about who is right.

K–2: Diversity of Life

• Some animals and plants are alike in the way they look and in the things they do, and others are very different from one another. • Plants and animals have features that help them live in different environments.

K–2: The Structure of Matter

• Things can be done to materials to change some of their properties, but not all materials respond the same way to what is done to them.

3–5: Diversity of Life

• A great variety of kinds of living things can be sorted into groups in many ways using various features to decide which things belong in which group. • Features used for grouping depend on the purpose of the grouping.

3–5: Scientific Inquiry

• Results of scientific investigations are seldom exactly the same, but if the differences are large, it is important to try to figure out why. One reason for following directions carefully and for keeping records of one’s work is to provide information on what might have caused the differences. • Scientists do not pay much attention to claims about how something they know about works unless the claims are backed up with evidence that can be confirmed with a logical argument.

6–8: Scientific Inquiry

• If more than one variable changes at the same time in an experiment, the outcome of the experiment may not be clearly attributable to any one of the variables. It may not always be possible to prevent outside variables from influencing the outcome of an investigation but collaboration among investigators can often lead to research designs that are able to deal with such situations.

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6–8: Diversity of Life

• Animals and plants have a great variety of body plans and internal structures that contribute to their being able to make or find food and reproduce. • For sexually reproducing organisms, a species comprises all organisms that can mate with one another to produce fertile offspring.

USING THE STORY WITH GRADES K–4 You might want to start by giving the probe “Needs of Seeds” in Uncovering Stu-

dent Ideas in Science: Volume 2 (Keeley, Eberle, and Tugel 2007). This probe asks students to choose what, among several choices, seeds need to germinate. It will also ask them to explain their thinking in their own words. This type of formative assessment will give you information you can put to use immediately. Try asking students to list those things they think are absolutely necessary for seeds to germinate. Even with young children, I would suggest using the correct term and making sure they understand what it means, which is where the animations are helpful. Using this list, change each one to a question. Each statement then becomes an investigable question. For instance, children usually say: • • • • • •

Seeds need sunlight to germinate. Seeds need fertilizer to germinate. Seeds need heat to germinate. Seeds need air to germinate. Seeds need water to germinate. Seeds need soil to germinate.

Change the first statement to, “Do seeds need sunlight to germinate?” and so on. Keep this list of questions visible during the teaching sequence to allow students to investigate each question and to keep the appropriate statements or delete them when they find out the results. You might also find useful information in “Seed Bargains” from Everyday Science Mysteries (Konicek-Moran 2008) or the prequel to this story “The New Greenhouse” in More Everyday Science Mysteries (Konicek-Moran 2009). Pick some fast-germinating seeds such as zinnia, marigolds, mung beans, or alfalfa. You should get results in a few days with these. If you plant the seeds in the soil close to the edge of a clear plastic cup, you will be able to see the roots mature beneath the surface of the soil. To answer the last question about seeds needing soil, I suggest placing seeds in a plastic sealed envelope or baggie with a moist paper towel. This will show them that soil is not necessary for seeds to germinate. If they haven’t grasped the concept of germination versus growing to maturity as a plant, this will help to establish the difference. Letting the students organize their plantings, control variables, and carry out the investigation will take quite a bit of help from you. They will have to figure out

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how to manage the seeds in containers so that all other variables are controlled. A good question to ask them if they fail to control variables is, “How will you know whether or not _____ was responsible for the germination?” Containers without moisture or warmth should not germinate but all others should, and these results will help to decide the important factors necessary for germination. Of course, the seedling in the container with the fertilizer should not come up any faster or healthier than the rest. This should, at a minimum, raise doubts about the necessity of fertilizer in the medium. I say this because some children will hold stubbornly to their prediction and may find some reason to infer that the fertilizer did make a difference. After all, for many people, “Seeing is believing.” This also leads into the critical-thinking skill of setting criteria for success. Some will believe that time is the variable that distinguishes success (the fastest germination). Remind them that they are testing to see if seeds germinate with or without certain conditions in the medium, not how fast they do it. You should strongly emphasize that not all seeds are able to germinate since they are not all equally healthy. This means planting several seeds in each container. The number of seeds that germinate should also not be a determinant of whether or not the experimental container has met all of the needs. The percentage of germinating seeds should remain fairly constant if you use this year’s seeds and plant them properly. For a look at suggestions for using trade books for this topic, NSTA members can access “Teaching Through Trade Books: What Happens to Seeds?” (Ashbrook 2005) or you can see what another teacher has done with this topic in the article “Cycling Through Plants” (Cavallo 2005). Both are available online at www.nsta.org. For very young children, you may want to focus on just one or two of the possible variables. For example, planting seeds in cups with too much water, no water, and just enough water can give important information to your students. They can also learn to control variables in this simpler type of investigation.

USING THE STORY WITH GRADES 5–8 For older children, I also suggest giving the probe “Needs of Seeds” (Keeley, Eberle, and Tugel 2007) as mentioned in the previous section. Formative assessment is so important that starting to teach without knowing what your students think about a concept is like heading out to sea in a rowboat without oars or a map and compass. It can also generate a discussion, especially if there is a lack of agreement on the part of the students. From this discussion, almost certainly, suggestions for testing ideas will result. Many of the ideas listed above will be pertinent to your approach to using the story with older children. They will be able to identify the variables involved in setting up the test to see if various things are necessary for the seeds to germinate. It is always advisable not to assume too much about how facile students are in designing investigations. They may well need your help in identifying variables

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that can be modified or kept the same. They may also need a refresher on designing investigations, which includes controlling variables. If you ask small groups of students to design a way to answer the questions, they can present their designs to the class for critique. I believe that it is important to help students to learn to give constructive criticism without being insulting. I usually ask them to begin by telling the group what they like about the design and then saying something like, “However, I have a problem with the fact that there is nothing in the design to keep track of the amounts of water/soil/fertilizer you will be using.” This technique may take the sting out of criticism and make the recipients less defensive and more receptive. As I have stated in the early chapters, we need to help our students to be communicators and be helpful to each other. We do not spend enough energy in teaching them how to “talk science” and to listen to others. NSTA members have free access to the journal article, “Bean Plants: a Growth Experience” (West 2004) at www.nsta.org. It is always helpful to find out what others have done with similar units. In this article, West describes how she carried out an investigation about the growth of bean plants and addressed her students’ misconceptions. She also includes a very useful rubric she designed for assessing the growth of her students’ knowledge about carrying out the investigation. Students who are older may also want to make the study a bit more complex by adding more questions regarding quantities of materials and graphing results. For example: • • • •

If a little water is good, is more better? Do seeds need deep soil to germinate? How much warmth do seeds need? Is any soil used up in the process of germination?

As in any activity designed to modify preconceptions that do not agree with the currently accepted ideas in science, your results should be fairly convincing that seeds need only three things to germinate and that fertilizer has no part of determining if a seed germinates. If, however, some students still hold fast to their previous ideas, be satisfied that you have helped to add another beam in the scaffolding that will someday result in their understanding the needs of seeds.

RELATED BOOKS AND NSTA JOURNAL ARTICLES Keeley, P. 2005. Science curriculum topic study: Bridging the gap between standards

and practice. Thousand Oaks, CA: Corwin Press. Keeley, P., F. Eberle, and C. Dorsey. 2008. Uncovering student ideas in science, volume 3: Another 25 formative assessment probes. Arlington, VA: NSTA Press. Keeley, P., F. Eberle, and J. Tugel. 2007. Uncovering student ideas in science, volume 2: 25 more formative assessment probes. Arlington, VA: NSTA Press.

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Keeley, P., and J. Tugel. 2009. Uncovering student ideas in science, volume 4: 25 new formative assessment probes. Arlington, VA: NSTA Press. Konicek-Moran, R. 2008. Everyday Science Mysteries: Stories for inquiry-based science teaching. Arlington, VA: NSTA Press. Konicek-Moran, R. 2009. More everyday science mysteries: Stories for inquiry-based science teaching. Arlington, VA: NSTA Press. Konicek-Moran, R. 2010. Even More Everyday Science Mysteries: Stories for inquirybased science teaching. Arlington, VA: NSTA Press.

REFERENCES American Association for the Advancement of Science (AAAS).1993. Benchmarks for science literacy. New York: Oxford University Press. Ashbrook, P. 2005. Teaching through trade books: What happens to seeds? Science & Children 42 (8): 18–20. Botanical Online SL. 2010. The germination of the bean. www.botanical-online. com/animation4.htm Cavallo, A. 2005. Cycling through plants. Science & Children 42 (8): 22–27. Driver, R., A. Squires, P. Rushworth, and V. Wood-Robinson. 1994. Making sense of secondary science: Research into children’s ideas. London and New York: Routledge Falmer. Keeley, P., F. Eberle, and J. Tugel. 2007. Uncovering student ideas in science, volume 2: 25 more formative assessment probes. Arlington, VA: NSTA Press. Konicek-Moran, R. 2008. Everyday Science Mysteries: Stories for inquiry-based science teaching. Arlington, VA: NSTA Press. Konicek-Moran, R. 2009. More everyday science mysteries: Stories for inquiry-based science teaching. Arlington, VA: NSTA Press. National Research Council (NRC). 1996. National science education standards. Washington, DC: National Academies Press. West, D. 2004. Bean Plants: A growth experience. Science Scope 27 (7): 44–47.

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Chapter 12

Dried Apples

J

ose is seven years old. He lives with his sister Maria, his mother, and his grandmother in the city. Jose is a second grader and he loves his school because he has so many friends there. Alex is his best friend. Jose and his family don’t travel much, so he was very excited when his teacher Mrs. Lopez told the class that they were going on a trip to the country.

They were going to visit an apple farm. “An orchard,” she called it. On Thursday, the day of the trip, Jose was very excited. The class boarded the bus and drove a long way out to the orchard. There were trees everywhere. All of them had apples hanging on them. There were green ones, bright red ones, some were even sort of yellow. The children got to pick apples from the trees and put

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them in boxes. It was fun. When they were leaving, the owner of the orchard gave the class a big box full of apples. There were many different kinds of apples. They had names like Macintosh, Northern Spy, Cortland, Granny Smith, and Delicious. The next day was Friday. Mrs. Lopez had plates with slices of the different kinds of apples on them. She asked the children to taste them and decided how they were all different or the same. Each child was to try a slice from each plate. Jose liked them all until he tried a Granny Smith. “Ooh,” he said, “that’s sour!” Jose didn’t want to eat any more so he put the plate with the Granny Smith slices on the windowsill behind his desk. “I’ll put the plate on the table later,” he thought. And he really meant to do it. But, soon he forgot all about it and at three o’clock the children were all excited about going home and thinking about the fun they were going to have over the weekend. Jose forgot all about the plate of apple slices. On Monday, Jose and his friends came back to their classroom and began their day. At snack time, Jose suddenly remembered his apple slices he had left on the windowsill. They were still there, right where he had put them. But, they were different. They were all brown. Not only that but they were shriveled up and wrinkled. He picked one up and it was light, flaky and almost dry. “What happened?” he said to Alex, his best friend. “It got eaten by mice,” said Alex. “But there are no tooth marks,” said Jose. “I don’t know,” said Alex, “they just dried up. Ask Mrs. Lopez.” Jose knew he would have to tell Mrs. Lopez about how he had put them on the windowsill. Maybe she would be angry. But she was a cool teacher and would understand. So he told her and asked her what she thought had happened. Mrs. Lopez was quite interested and called all of the children around her. They gathered in the meeting area. Jose told them his story and Mrs. Lopez asked them to tell her what ideas they had to explain what happened to the apples. She wrote them down on a big sheet of paper.

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PURPOSE Water makes up a very high percentage of all living things. This story is aimed

at providing children with the opportunity to measure the surprising amount of water found in fruit. It also provides an opportunity for the teacher to emphasize the importance of water in our lives. However, the story is multifaceted and it takes advantage of the curiosity of children about different textures and tastes and encourages them to experiment with foods they are not accustomed to eating. It also addresses the concept of variety in a common fruit, the apple, and could possibly lead to questions about the purpose of a fruit and how it comes to be.

RELATED CONCEPTS • Needs of organisms • Evaporation • Diversity of living things

• Water • Senses

DON’T BE SURPRISED This chapter’s story had its conception while I was participating in a second-grade

lesson using students’ apple preferences to integrate literature, math, and science. The teacher read the story of Johnny Appleseed to the students prior to their tasting different kinds of apples and graphing their preferences. Some of the students observed that some of the apples seemed juicier than others. This led to a realization that there might be more to the science part of the lesson than just tasting the apples. This story was written and then tested in another second-grade class. Many classes have made “shrunken heads” out of apples by carving faces in the peeled apples and hanging them up until they dried. The effect is dramatic and is a favorite Halloween activity. The dramatic reduction in size in the apples provides evidence of the amount of water in this familiar fruit and eventually in all living things. For many students, apples are apples and the idea of water making up a substantial part of apples or other fruits is not apparent. The idea that bodies of plants and animals (including humans) are mostly water seems equally absurd! However, making apple cider might be an experience some have had and they know that apple juice has to come from somewhere. Many will not realize that raisins are dried grapes and prunes are dried plums. Since there are ample opportunities for quantitative data, integration with math is a logical connection.

CONTENT BACKGROUND If you test various apples, you will find that they are quite different in appearance

and taste. Some do appear to be juicier and that leads to the question, do some

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apples contain more water than others? If you are able to borrow a digital scale that will measure with a sensitivity of 0.1 g you may find some differences among the types of apples. But, even with a primitive one-gram primary balance, the weight loss after drying out will be dramatic. The major point is that the apples usually lose more than 80% of their weight when they dry out. Slicing the apples into approximately equal eighths will provide enough exposure, and they will dry out nicely in a few days to a week. Apples, as well as all living things, require water to replenish water lost to the environment in many ways. Apples have waxy skin that protects the soft flesh inside from losing water to the air. When this skin is peeled away, the apple responds almost immediately losing water to the atmosphere. Life cannot exist without water. This is one reason that astronomers and other scientists are trying to find out whether there was ever water on other planets in our solar system. Humans can fast for weeks without lethal results but can last only days without water. It is estimated that the human body is composed of about 66% water. Most students will be amazed at the amount of water lost when a living thing such as an apple dries out. Cells are composed mostly of water and living things are made up of cells. Animals and plants that live in dry climates, such as deserts, have adapted to protect themselves from losing water. Plants have waxy, succulent leaves to keep water from evaporating into the dry air. Animals excrete very little urine and are adapted to obtaining water from the food that they eat. Some animals actually become dormant during dry seasons. Some plant seeds will remain dormant for years until water is again abundant enough for them to germinate. Fish and other aquatic animals lay their eggs in water-retaining algae before the dry seasons so that their eggs will live until the next rains fall. Trees such as the bald cypress in semitropical climates, where there are long dry periods, lose their leaves until the rainy season returns. Since the fruits of plants contain the seeds of the next generation, plant adaptations strongly protect these seeds from dehydration. One could almost say that all successful animals and plants have adapted in some way to retain the precious fluid, despite environmental conditions that would steal it from them. Apples, of course, are the structures that apple trees use to protect and disseminate their seeds, the doors to the next generation. Luckily for us, they also provide us with a delicious repast. This is a definite survival plus for the tree since it means that animals delight in eating the fruit and thus releasing the seeds into the surrounding territory. It is not an accident that the fleshy fruit surrounds the seeds. It is definitely in the best interests of the survival of the plant to have its fruit be an attraction to wildlife, including humans. This information is provided in case you wish to branch off into blossoms, the formation of fruit, and the release of seeds.

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Related Ideas From the National Science Education Standards (NRC 1996) K–4: The Characteristics of Organisms

• Organisms have basic needs. For example animals need air, water, and food; plants require water, nutrients, and light.

5–8: Diversity and Adaptations of Organisms

• Millions of species of animals, plants, and microorganisms are alive today. Although different species might look dissimilar, the unity among organisms becomes apparent from the analysis of internal structure, the similarity of the chemical processes, and the evidence of common ancestry.

Related Ideas From Benchmarks for Science Literacy (AAAS 1993) K–2: Cells

• Most living things need water, food, and air.

6–8: Cells

• About two-thirds of the weight of cells is accounted for by water, which gives cells many of their properties.

Using the Story With Grades K–4 After the story has been read to the students, they will have various ideas

about why the apples shriveled, dried up, and lost weight. After you have recorded these ideas, there are two questions that usually come up: “Where has the juice in the apple gone?” and “Does the type of apple make a difference in how much juice is lost?” We have found that a good way to begin is to recreate the situation portrayed in the story and have several types of apples to taste. There may be an excursion into where the juice has gone. Then it becomes time to design a way to find out if there are differences in weight loss among the apples. Although children need help in thinking of all of the variables, they will probably insist that all of the apple slices weigh the same. This can be accomplished by paring the slices down to a common size and weight. They may also want to know if half an apple will dry out as fast as a small slice, or if a peeled apple specimen will dry out faster or more than an intact section. Remember to ask for reasons when they make a prediction. All records should

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Chapter 12

be kept in their science notebooks. At this grade level we find that drawings are a favorite way for students to keep records. Try to help them to use good labeling techniques so that they will remember what their drawings mean later. If students are disappointed if they do not find large differences in the various apple weight loss, be sure to tell them that they have found an answer to their questions and sometimes the answer is not what they had hoped. Above all, the students are guaranteed to find a tremendous weight loss overall and this should be stressed because it is important for them to realize how much of the body weight of living things is composed of water. Some students may recall seeing dried up bodies of animals such as frogs or toads. These experiences will add to their realization that all living things consist mainly of water. These experiments may lead to the application of this knowledge including the making of applesauce and the fact that grocery shelves are full of juices made from just about any fruit imaginable. You may have to help them to realize that fruit juices are really water with flavor from the essence of the individual fruit. Many students have had the experience of mixing concentrates with water to make juice. This may help them to make the connection.

Using the Story With Grades 5–8 Changing the age and grade level of Jose might be a good place to start when

using this story with older students. Feel free to modify the story in any way that would make it more appealing to your grade level. Trying different types of apples is still an enjoyable activity for older students and the apple weight loss should still be somewhat mysterious to your students regardless of their experience. With older students, the measurement of weight loss should present few problems. I still suggest starting with an “Our Best Thinking Until Now” chart in order to get students ideas out in the open. Changing these statements to questions and then to predictions is standard procedure in all of the stories. Be sure to require a reason for each prediction so students realize that predictions are not merely wild guesses. Designing the investigations to test these predictions should be done carefully and slowly, involving the whole class taking part in critiquing the designs of smaller groups who are carrying out specific investigations. Students of this age often wonder if the weight loss seen in apples is also true of other fruits such as pears, oranges, bananas, cherries, and so on. Many will have either seen or tried dried fruits as part of trail mixes or granola-type cereals. Drying and comparing these other fruits can be accomplished slowly without special equipment or more quickly in a commercial fruit dryer. Perhaps one of your colleagues has one that can be borrowed. This method of preserving food has been used for centuries before the invention of refrigeration. As you can see, this area of questions has few limits and can proceed as far as you are willing to take it, acting upon the limits of student interest. These activities and experiments fall within the category of the “What would happen if…” or “I wonder if…” type questions that are so

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productive. Encouraging your students to pursue these types of questions leads to true inquiry. It is also a wonderful opportunity for you to integrate math and science in calculating the percentages of water in various fruits, which connects nicely to the use of mathematics as described in the 5–8 NSES inquiry standards.

Related Books and Journal Articles Driver, R., A. Squires, P. Rushworth, and V. Wood-Robinson. 1994. Making sense

of secondary science: Research into children’s ideas. London and New York: Routledge Falmer. Keeley, P. 2005. Science curriculum topic study: Bridging the gap between standards and practice. Thousand Oaks, CA: Corwin Press. Keeley, P., F. Eberle, and L. Farrin. 2005. Uncovering student ideas in science: 25 formative assessment probes, volume 1. Arlington, VA: NSTA Press. Keeley, P., F. Eberle, and J. Tugel. 2007. Uncovering student ideas in science: 25 more formative assessment probes, volume 2. Arlington, VA: NSTA Press.

References American Association for the advancement of Science (AAAS). 1993. Benchmarks for science literacy. New York: Oxford University Press. National Research Council (NRC). 1996. National science education standards. Washington, DC: National Academies Press.

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Chapter 12

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Chapter 13

Plunk, Plunk

P

lunk… Plunk. “What’s that noise?” thought Sam, as he sat in the dining room doing his math homework. Dad was in charge of supper tonight. Mom was at a meeting. Plunk. There it was again. Birds? Someone throwing stones at the window?

Sam snuck over to the window and peered around the curtain—no one was there. Dad was in the kitchen. Did he hear it? Nah, he was humming along with some public radio music. When he was doing that, he didn’t even hear the telephone. Plunk… plunk. Plunk… plunk! “What is this?” he asked out loud. This was becoming annoying!

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Sam listened again. No sound. Guess it stopped. Back to the homework. PLUNK! “All right! This has gone far enough,” he exclaimed! He figured out that it was coming from the kitchen, so he stealthily snuck toward the kitchen door and bounded inside just as another “plunk” hit his ear. Nothing, nobody—just Dad grating cheese and the dog sitting prettily in front of him with a longing look on her face. Plunk. “Now I’ve got you!” he thought. The sound came from the counter and as he watched in amazement, he saw a pea, from a bowl of peas soaking on the counter, roll off the top, and hit the tray on which the bowl was sitting. Plunk. Sam hunkered down, both elbows on the counter and stared at the bowl. “C’mon,” he dared it. “Do it again!” Nothing. Sam waited. Then, with an almost magical effect, one of the peas at the edge of the bowl began to move and slowly rolled over the edge and dropped. Plunk! “What’s in there?” he asked. “Mice?” Another pea fell. Plunk. “Whoa! This is weird. Dad, look at this. Didn’t you hear anything?” Dad stopped his humming and grating and came over. “What am I supposed to be looking at?” he asked. “Watch the peas,” directed Sam. After what seemed like ages, sure enough, another pea fell off the pile. Plunk! “I filled this bowl with peas and then added water to soak them for tonight’s pea soup, that’s all. Look, there must be two dozen that jumped out of the bowl, and they’re still doing it. There must be something in there eating them or pushing them up or something,” said Dad. They carefully began to empty the bowl, waiting for the critter to be exposed. No, critter, only water and peas. “This is weird,” whispered Sam. “Do you think we can we make it happen again?”

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PURPOSE What happens when seeds are soaked in water? This story offers students an

opportunity to see the incredible capacity of seeds to take in water, soften their seed coats, and ready themselves for germination. The changes are physical, but the results allow the seed to begin the chemical processes that lead to the birth of a new plant. This activity also gives the students an opportunity to engage in investigations on the amount of water that various seeds can absorb and to sharpen their inquiry skills along with their mathematical prowess. Can soaked seeds be planted and growth recorded? Certainly, and as an added value, students who are ELL and come from countries where beans are a real food staple can find a great deal to talk about. This adds to the cultural learning of the class and to the ELL students’ greater participation in the class discussions. I would like to give credit to the AIMS (Activities for Integrating Math and Science) Educational Foundation whose activity “It’s Bean Swell” I have used with students for years with great success. The activity is now back in print in revised form called “Seed Soakers,” in Primarily Plants (AIMS 2005).

RELATED CONCEPTS • Germination

• Inquiry skills • Calculating area and percentage of change

DON’T BE SURPRISED You may find that your students cannot perceive of seeds absorbing so much water,

for they may equate them with how a sponge soaks up water. They also may not understand that inside this seed is a plant that uses the water to ready itself for germination. Grocery store seeds (peas and beans) are looked on as food and not as potential plants. You yourself may be surprised at the tremendous amount of growth in mass and size that soaking seeds take in.

CONTENT BACKGROUND Cooking is full of everyday science mysteries like this one. Beans swell consider-

ably when soaked. The seeds used in the story could be lima beans, black-eyed peas, split peas, kidney beans, garbanzos, lentils, or any other type of bean Sam’s father was soaking for an evening meal. Depending upon the type of bean, some swell as much as three times the size of the dry bean. Most seeds selected for sale are dried for a long shelf life in garden or grocery stores. Otherwise, they would ferment, mold, or sprout. All of these would make the seed useless for cooking or planting. Most cooks, like Sam’s father, prefer to

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place beans in water for about four hours so that the dried beans can rehydrate and cook more quickly and evenly. In addition, beans are usually dirty with “field dirt,” which may include insect parts, gravel, soil, or rodent by-products. Thus soaked beans should be thoroughly rinsed. Also, beans contain a substance called phytic acid that inhibits our bodies from absorbing such minerals as iron, magnesium, calcium, and zinc. Much of this acid can be removed by soaking the beans in water before cooking. A cook’s rule of thumb is that a cup of dry beans will yield about three cups of cooked beans. Simple mathematics tells us that we need to use about three cups of water for every cup of beans in the soaking process. But enough food science for now. Now on to the process of how the beans take in water and to what extent the water affects the swelling and the weight increase of the beans. On the pea or bean, what we call legumes, one can find a small scar called a hilum on the inside of the curved surface of the seed. This scar is formed when the seed breaks away from its connection to the fruit surface. (Remember in botanical lingo even vegetables are called fruits! hilum Everything that holds a seed is a fruit.) If you open a fresh pea pod, you can see that as you remove the pea, you must unhitch it from a tiny umbilical-like bridge. The hilum leaves an opening in the seed through which water can readily pass into the seed. Beans often swell to an extent that they become larger than the amount of water taken in would warrant. This process is called imbibition. The water enters into the seed and is absorbed by polymers within the seed that are attracted to water molecules. A polymer is defined as a large molecule built of repeating units of cellular structures. Many people equate the term with plastics, but in fact, polymers are found commonly in the natural world. In legumes, the polymers in the seed somehow amplify the size of the swelling past the amount of water taken in. The process is not fully understood, but this anomaly will become apparent to middle school students who choose to follow up on a suggested study of the amount of water versus the amount of swelling challenge presented to them in the Using the Story With Grades 5–8 section on page 135. If you lead the students toward dissecting the soaked seeds, they will find, in most seeds, the young plant. In legumes such as peas and beans, they’ll be able to see the two seed leaves, cotyledons, and the small early root called the radicle. When we eat beans, we are eating the cotyledons and getting lots of fiber and carbohydrates but very little fat.

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Beans have been cultivated for approximately the past 10,000 years. The Native Americans added two crops, corn and squash, to the bean field to form the “three sisters,” a balanced diet creating the complete protein needed in our diet. Corn is a notorious nitrogen user, and beans, like all legumes, are known for fixing nitrogen—absorbing nitrogen from the atmosphere and putting it back into the soil in a useable form. So this practice is also of benefit to the soil ecology. Over the ages, beans were eaten raw, cooked, fermented into soy sauce or miso, ground into flour, or made into tofu. Beans do, however, produce a great deal of gas during digestion. This is because beans contain a sugar called oligosaccharide that humans do not possess the enzyme to break down. It reaches our lower intestine and ferments producing the gas that is released, often, it seems, in the company of others causing some embarrassment! Soaking the beans does take out a lot of the sugar so that home cooking has a beneficial effect on this little problem. Despite this, a diet rich in beans can be a healthy one, lowering bad cholesterol (HDL); providing lots of good minerals, vitamins, and fiber; and helping to keep weight down.

RELATED IDEAS FROM the NATIONAL SCIENCE EDUCATION STANDARDS (NRC 1996) K–4: Abilities Necessary to Do Scientific Inquiry • • • • •

Ask a question about objects, organisms, and events in the environment. Plan and conduct a simple investigation. Employ simple equipment and tools to gather data and extend the senses. Use data to construct a reasonable explanation. Communicate investigations and explanations.

K–4: The Characteristics of Organisms

• Organisms have basic needs. For example, animals need air, water, and food; plants require air, water, nutrients, and light. Organisms can survive only in environments in which their needs can be met. • The world has many different environments, and distinct environments support the life of different types of organisms. • Each plant or animal has different structures that serve different functions in growth, survival, and reproduction.

K–4: Life Cycles of Organisms

• Plants and animals have life cycles that include being born, developing into adults, reproducing, and eventually dying. The details of this life cycle are different for different organisms. • Plants and animals closely resemble their parents.

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5–8: Abilities Necessary to Do Scientific Inquiry • • • •

Identify questions that can be answered through scientific investigations. Design and conduct a scientific investigation. Use appropriate tools and techniques to gather, analyze, and interpret data. Think critically and logically to make the relationships between evidence and explanations.

5–8: Structure and Function in Living Systems

• Living systems at all levels of organization demonstrate the complementary nature of structure and function. Important levels of organization for structure and function include cells, organs, tissues, organ systems, whole organisms, and ecosystems.

5–8: Reproduction and Heredity

• Reproduction is a characteristic of all living systems because no individual organism lives forever. Reproduction is essential to the continuation of every species. Some organisms reproduce asexually. Other organisms reproduce sexually.

5–8: Diversity and Adaptations of Organisms

• Millions of species of animals, plants, and microorganisms are alive today. Although different species might look dissimilar, the unit among organisms becomes apparent from an analysis of internal structures, the similarity of their chemical processes, and the evidence of common ancestry.

RELATED IDEAS FROM BENCHMARKS FOR SCIENCE LITERACY (AAAS 1993) K–2: Scientific Inquiry

• People can often learn about things around them by just observing those things carefully, but sometimes they can learn more by doing something to the things and noting what happens. • Describing things as accurately as possible is important in science because it enables people to compare observations with those of others. • When people give different descriptions of the same thing, it is usually a good idea to make some fresh observations instead of just arguing about who is right.

K–2: Diversity of Life

• Some animals and plants are alike in the way they look and in the things they do, and others are very different from one another. • Plants and animals have features that help them live in different environments.

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K–2: The Structure of Matter

• Things can be done to materials to change some of their properties, but not all materials respond the same way to what is done to them.

3–5: Diversity of Life

• A great variety of kinds of living things can be sorted into groups in many ways using various features to decide which things belong in which group. • Features used for grouping depend on the purpose of the grouping.

3–5: Scientific Inquiry

• Results of scientific investigations are seldom exactly the same, but if the differences are large, it is important to try to figure out why. One reason for following directions carefully and for keeping records of one’s work is to provide information on what might have caused the differences. • Scientists do not pay much attention to claims about how something they know about works unless the claims are backed up with evidence that can be confirmed with a logical argument.

6–8: Scientific Inquiry

• If more than one variable changes at the same time in an experiment, the outcome of the experiment may not be clearly attributable to any one of the variables. It may not always be possible to prevent outside variables from influencing the outcome of an investigation but collaboration among investigators can often lead to research designs that are able to deal with such situations.

6–8: Diversity of Life

• Animals and plants have a great variety of body plans and internal structures that contribute to their being able to make or find food and reproduce. • For sexually reproducing organisms, a species comprises all organisms that can mate with one another to produce fertile offspring

USING THE STORy WITH GRADES K–4 Of course the children will want to reproduce the incident in the story, but

with your guidance they should first be asked to hypothesize what will happen to each of the types of seeds in the cups when filled with the water. Groups of four or five students can share a cup of about three ounces. Try to use clear plastic cups so that they can see what is happening inside. Each group should have two cups for each type of seed so that they can use one to hold seeds without water as a control. I suggest that you get at least two different kinds of beans. I prefer limas because they absorb so much water, but black-eyed peas or garbanzo beans or even

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split peas will do. It might also be interesting to use corn kernels as well to compare a seed from a different kind of plant, a monocot. The idea here is to allow students to compare what happens to at least two different seeds. The first step might be to allow the students to examine the seeds closely with a hand lens. They should also draw them in their science notebooks. Then ask them what they think happens to the seed when it is watered. These answers should be recorded on a large sheet of paper for future reference. These can be used to help them set up an investigation. There will be a few ideas that can be tested and at this time you can help them design a fair test. They may not think of using a control (seeds without water), but you can ask them how they will know what would have happened if no water had been added to a cup of seeds. Questions might include • How will you know if the seed has changed? • How will you know it was the water that made any of the differences you might find? • How long do you think it will take for any changes to take place? • Will the seeds grow if we plant them after the investigation? • Will soaked seeds germinate faster than dry ones when planted in soil? Let the children set up their investigations according to an agreed upon design so that the whole class is doing the same thing at the same time, unless you are comfortable with having several different investigations going on simultaneously. Be sure to stress that if you are going to consider size changes within a framework of time, they all need to start and check their results at the same time. I suggest that you start this activity in the morning and let the beans soak for about four hours. Be sure to measure the weight and size of the seeds before soaking. Placing the seed on centimeter graph paper and seeing how many squares the seed covers could do this, repeated after soaking to see the difference. Drawing around the seed before and after will also make a good record. These seeds should be kept separate from the others or marked in some way for identification later on. Normally elementary classrooms do not have scales accurate enough to weigh individual beans, but if the children weigh all of the beans before and after soaking, the amount of weight gain will still seem amazing to them. The activity usually works best if you place the beans in the cup first, up to the brim and then add a measured amount of water, also up to the brim. Children can check their setups every hour to see what is happening. The water may eventually not cover the seeds, so more will be needed. If that is the case, have the children measure how much water they add each time. When, as in the story, the beans start to fall out of the cups, note the time and see how many beans fall out each hour. You may want to add water at this time with an eyedropper so the water does not overflow and contaminate your data. This will keep the seeds down deep in the cup moist and allow them to continue to swell. Have the children finish the story in writing with an explanation as to what they think happened. They can also make observations on how long it takes

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each kind of seed to use up all of the water or how long it takes before the first seed falls out. When time is up, they can remove the beans and measure the amount of water left in the cup and compare that to how much they added. If you wish to go further with this story, you may want to have the children peel off the softened seed covering and open the seed to see what is inside. This will also give them an idea of how the plant makes its way through the tough seed coat. They can draw what they see and you can help them see the beginnings of the new plant, particularly the cotyledons and the new root. The dicotyledons (dicots) will have two leaves, and the monocots such as corn with have only one. Putting the seeds into a sealed plastic bag with a wet paper towel and taping them to the window can also provide an opportunity to see what happens to the seeds once water has awakened the dormant plant inside the seed. Be prepared for some mold after a certain amount of time, so there is a limit to how long the seeds can be observed in the bags. Of course, the seeds may be planted in soil and you can continue on as long as you or the children wish with this part of the investigation. Even though it goes beyond the story, it is a logical extension and may be worth following, particularly if the children are excited about it.

USING THE STORy WITH GRADES 5–8 Older students are just as intrigued by the story as younger ones. In fact, they are very anxious to get started on “make it happen again.” Of course you will want to start them off with recording their thoughts about seeds and soaking. Then the design of an investigation comes next and, with your leadership, a good discussion on this should involve their agreeing on a specific procedure involving a control. I have found that older students are insistent on using more kinds of seeds. This may be because they are more aware of the various types of seeds available or maybe they’re just more curious. Older students are capable of carrying out multiple investigations and keeping track of their data. In fact, this may be so easy for them that they are ready for a more challenging kind of investigation in the form of another story. I will include the story below as a possible extension of the investigation.

Extension Story to “Plunk, Plunk” Mary, Jim, and Helen have been having an argument about beans. They are all aware that lima beans placed in a container of water swell to a proportionately greater amount compared to their original dry amounts. They gain both mass and volume. But the trio disagree on the following points: Mary says, “The beans swell up and gain proportionally more in volume than in mass. You can look at them and see that! They look twice as big but they can’t possibly weigh twice as much.”

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Jim says, “The mass of the beans grows proportionally more than the volume. All you have to do is hold them in your hand to see that! They have absorbed all of that water, but the amount of mass gained seems to be more than that of the volume somehow. I’ll bet their mass triples while the volume only doubles.” Helen says, “The amount of mass and volume gained have to be the same. Equal. The swelling is due to the water the beans have absorbed, and the volume increase is made up of water so the weight gain has to equal the weight of the water they took in.” What kind of experiment could be carried out by the trio to settle the question? You may work in groups of four. Form a hypothesis or multiple hypotheses in your group and carry out an experiment to settle the question. Volume measuring materials are available in the room. Please try to reach a consensus on the design of your experiment.

Content Background to Extension Story Oddly enough, Mary is right. This is the amplification or exaggeration in swelling

I mentioned before. It is due to the fact that the swelling is enhanced by the polymers in the bean seed. This, however, is not the point of the activity. The purpose is to get the students to design a very difficult investigation. Helen’s explanation seems to make the most logical sense but does not take into account the seeds’ erratic behavior. The difficult part is to gather information on the volume of the bean seeds. They do sink, so the displacement of water is the best way to gather these data. You should use more than one bean to get readable results and then keep those seeds separated from any others so that they can be retested at the end of the investigation. This information about erratic swelling in beans comes from a paper, Volumetric Components of Seed Imbibition, in the journal Plant Physiology, by A. Carl Leopold (1983) of the Boyce Thompson Institut, (www.plantphysiol.org/cgi/ reprint/73/3/677.pdf ). The paper is not difficult to understand and if you tell the students about the study, it makes the activity all the more relevent. After all, a real scientist cared enough about the problem to study it and write a paper on it. And a prestigious journal agreed to print it. How close to being a scientist can you get?

RELATED BOOKS AND JOURNAL ARTICLES Driver, R., A. Squires, P. Rushworth, and V. Wood-Robinson. 1994. Making sense

of secondary science: Research into children’s ideas. London and New York: Routledge Falmer. Keeley, P. 2005. Science curriculum topic study: Bridging the gap between standards and practice. Thousand Oaks, CA: Corwin Press.

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Keeley, P., F. Eberle, and C. Dorsey. 2008. Uncovering student ideas in science: Another 25 formative assessment probes, volume 3. Arlington, VA: NSTA Press. Keeley, P., F. Eberle, and L. Farrin. 2005. Uncovering student ideas in science: 25 formative assessment probes, volume 1. Arlington, VA: NSTA Press. Keeley, P., F. Eberle, and J. Tugel. 2007. Uncovering student ideas in science: 25 more formative assessment probes, volume 2. Arlington, VA: NSTA Press. Konicek-Moran, R. 2008. Everyday science mysteries. Arlington, VA: NSTA Press. Konicek-Moran, R. 2009. More everyday science mysteries. Arlington, VA: NSTA Press.

REFERENCES AIMS Education Foundation. 2005. Seed soakers. In Primarily plants, 57–65. Fresno, CA: AIMS. American Association for the Advancement of Science (AAAS). 1993. Benchmarks for science literacy. New York: Oxford University Press. Leopold, A. C. 1983. Volumetric components of seed imbibition. Plant Physiology 73: 677–680. National Research Council (NRC). 1996. National science education standards. Washington, DC: National Academies Press.

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Chapter 14

Hitchhikers

I

t was a brisk autumn evening and Annie, the fouryear-old golden retriever, was eager for a postsupper walk. Kelsey enjoyed walking Annie because she was such a well-behaved dog. Well, usually, but tonight she pulled the leash out of Kelsey’s hand to chase the resident groundhog out of the yard and into the vacant field next door. Kelsey raced after her, worried that Annie might end up on the busy road nearby and meet up with

a speeding car. She followed the barking sounds and finally found Annie yapping at a hole in the ground into which the groundhog had retreated. “Come on Annie, you’ll never get him out of there now, and even if you did, he’s got some pretty sharp teeth. Not a good idea!” Kelsey grabbed the leash tightly this time and tugged Annie away from the hole and back across the field through the waist-high weeds.

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When they emerged from the field and into the yard, they were covered with little objects that stuck to every part of their clothes and fur. Annie needed a complete grooming since she immediately began to chew on her fur trying to get the things out of her coat. Kelsey’s pants and sweater were covered with them and they did not come off easily. When they went inside, everyone told her not to drop her mess on the floor. “Don’t worry!” she answered, “I can hardly pull them off. They won’t fall on the floor, that’s for sure. Some of them are so prickly they hurt my fingers when I grab them. They’re seeds, right?” “I sure think so,” said Dad. “I wonder if they would grow if I planted some?” “Well, they don’t usually come up until spring or summer, so you might have a long wait.” “Do they count on Annie and me to carry them around?” “Well, they have to get around somehow and you and Annie were handy,” said her sister Beth. “Suppose Annie and I weren’t out there today? What then? There must be other ways for seeds to get around besides covering me with stickers,” complained Kelsey. Dad had an idea. “I think there are a lot of ways that seeds travel, Kelsey. Why don’t we go on a seed hunt and see if we can figure out how they all travel away from their parent plants?” And so they did. They were able to collect lots of different seeds and it really wasn’t so hard to figure out their forms of transportation once they looked at all of them very carefully.

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PURPOSE Seed plants have evolved in many ways over the eons. This story explores one of

the important characteristics of plant evolution: the wide distribution of seeds so that they do not compete for sunlight, water, and nutrients in the same area as their parents. We have already looked at the flying seeds of sycamore and maple trees in “Trees From Helicopters” (see Chapter 5). Now we will explore the other ways seeds “leave home” once they are ready to germinate. I should add that the term seed is often used when fruit is more appropriate. Most plants disperse fruits that contain seeds. This story, with appropriate observation of the ways in which common plants distribute their seeds and fruits, can develop a new awareness about plants in your students.

RELATED CONCEPTS • Plant life • Reproduction • Life cycles • Fruits and seeds

• Adaptation • Form and function • Seed dispersal

DON’T BE SURPRISED Students are usually not aware that seed plants have adapted to overcrowding by

developing mechanisms that disperse their seeds to other locations. Even though most children who have walked in a field have experienced the fruits that stick to their clothes, they do not know the value of this to the plant or that they are carrying away fruits that contain seeds. Seeds are seldom, if ever, naked in flowering plants but are either attached to or part of a fruit. Mistaking fruits for seeds is common in both children and adults.

CONTENT BACKGROUND As plants evolved to include the flowering plants or angiosperms, those plants that

were able to send their seeds away from the parent plant were more likely to produce a new generation of healthy and productive plants. Young plants that do not have to compete with their parents for light, water, and nutrients are more likely to survive and, at the same time, not impinge on the parent’s ability to live and reproduce. So natural selection helped favor the plants that dispersed their seeds to distant locations. There are several methods that plants use to disperse their seeds: animals, wind, gravity, water, and fire. Following is a discussion of each.

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Figure 14.1 Burdock fruit

Figure 14.2 Bidens

Figure 14.3 Wind-borne fruit

Figure 14.4 Red mangrove propagule

Dispersal by Animals: The story tells about one kind of plant, a cocklebur (Xanthium strumarium), that has fruit with tiny hooks on the surface, guaranteed to stick to any animal that brushes against it. But not all animal-dependent fruits are hitchhikers. Some seeds are within fruits that animals eat. Acorns, the fruit of the oak trees, are gathered by squirrels and often buried. Many are not found again and germinate in the soil where they had been put. Other fruits are delicious to animals and eaten on the spot. Later, the seeds pass through the digestive tract and are eliminated in a different place far from the parent. Do you remember ever having eaten an apple and throwing away the core containing the seeds? This is an example of an inedible seed that is dispersed in yet another way. As a note of interest, the hook-and-loop system of the hairs on the hitchhiking burdock fruit (Arctium pubens) was the inspiration for Swiss inventor George de Mestral to create Velcro (see Figure 14.1). Bidens (Figure 14.2), such as Bidens aristosa, also disperse by clinging to clothes and hair. Dispersal by Wind: Other plants depend upon the wind to carry their seeds away. Elms, maples, sycamores, and others have winged fruit that act like helicopters to carry the fruits away. Milkweed (Asclepias syriaca), dandelions (Taraxacum officinale), and other plants from the Aster family (Asteraceae) produce fruits that are like parachutes. Who among us has not blown the mature fruits of the dandelion away into the breeze? The entire parachute is the fruit and the seed is attached to the bottom end of the parachute stalk. Trees like the willow and poplar also produce parachutelike fruits that are windborne (Figure 14.3). Dispersal by Gravity: Gravity and shape also combine to take fruits away from the parent plants. Ripe fruits like chestnuts and buckeyes (what we used to call “conkers”) drop to the ground and because they are round will roll a distance away. Dispersal by Water: Another way that fruits and seeds escape from the parent plant is by floating away in water. Water plants, or those that live on or above a stream, lake, or even an ocean, drop their fruits into the water and allow the currents to carry the fruit away. The red mangrove (Rhizophora mangle) actually germinates its seeds on the plant and then drops a cigar-shaped plant into the shallow marine waters in which the mangrove thrives (Figure 14.4). The propagule, as it is called, floats upright in the water until it touches a proper substrate (a particular set of soil conditions needed for the plant to survive), where it puts out anchoring roots and begins its life. Coconut palms (Cocos nucifera) also drop their fruit into the water and float long distances—even from one tropical island to another. Dispersal by Fire: Finally, some plants, such as the jack pine (Pinus banksiana), need fire to release their seeds. Heat from fire melts

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the protective wax that holds the seeds in place on the cone. The seeds are not released until this happens. The seeds also need a substrate that has been burned away to germinate. This is why fire is essential in many forests for smaller plants to get a start. In many national parks, burning is done on purpose in safely controlled situations (called prescribed burns) so that newer plants can get a start and have fewer competitors for resources. Fire may occur naturally but when it does not, certain areas may be burned on a regular basis to preserve the ecological integrity of the area.

RELATED IDEAS FROM the NATIONAL SCIENCE EDUCATION STANDARDS (NRC 1996) K–4: The Characteristics of Organisms

• Organisms have basic needs. For example, animals need air, water, and food; plants require air, water, nutrients, and light. • Each plant or animal has different structures that serve different functions in growth, survival, and reproduction.

K–4: Life Cycles of Organisms

• Plants and animals have life cycles that include being born, developing into adults, reproducing, and eventually dying. The details of this life cycle are different for different organisms. • Plants and animals closely resemble their parents.

K–4: Organisms and Environments

• All animals depend on plants. Some animals eat plants for food. Other animals eat animals that eat plants. • All organisms cause changes in the environment where they live. Some of these changes are detrimental to the organism or other organisms, whereas others are beneficial. • Humans depend on their natural and constructed environments. Humans change environments in ways that can be either beneficial or detrimental for themselves and other organisms.

5–8: Structure and Function in Living Systems

• Living systems at all levels of organization demonstrate the complementary nature of structure and function. Important levels of organization for structure and function include cells, organs, tissues, organ systems, whole organisms, and ecosystems.

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• Specialized cells perform specialized functions in multicellular organisms. Groups of specialized cells cooperate to form a tissue, such as a muscle. Different tissues are in turn grouped together to form larger functional units, called organs. Each type of cell, tissue, and organ has a distinct structure and set of functions that serve the organism as a whole.

5–8: Reproduction and Heredity

• Reproduction is a characteristic of all living systems; because no individual organism lives forever, reproduction is essential to the continuation of every species. Some organisms reproduce asexually. Other organisms reproduce sexually.

5–8: Regulation and Behavior

• All organisms must be able to obtain and use resources, grow, reproduce, and maintain stable internal conditions while living in a constantly changing external environment. • An organism’s behavior evolves through adaptation to its environment. How a species moves, obtains food, reproduces, and responds to danger is based in the species’ evolutionary history.

5–8: Populations and Ecosystems

• The number of organisms an ecosystem can support depends on the resources available and abiotic factors, such as quantity of light and water, range of temperatures, and soil composition. Given adequate biotic and abiotic resources and no disease or predators, populations (including humans) increase at rapid rates. Lack of resources and other factors, such as predation and climate, limit the growth of populations in specific niches in the ecosystem.

RELATED IDEAS FROM BENCHMARKS FOR SCIENCE LITERACY (AAAS 1993) K–2: Evolution of Life

• Different plants and animals have external features that help them thrive in different kinds of places.

K–2: Diversity of Life

• Some animals and plants are alike in the way they look and in the things they do and others are very different from one another.

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K–2: Heredity

• There is variation among individuals of one kind within a population. • Offspring are very much, but not exactly, like their parents and like one another.

3–5: Diversity of Life

• A great variety of kinds of living things can be sorted into groups in many ways using various features to decide which things belong to which group.

3–5: Evolution of Life

• Individuals of the same kind differ in their characteristics and sometimes the differences give individuals an advantage in surviving and reproducing.

6–8: Diversity of Life

• Animals and plants have a great variety of body plans and internal structures that contribute to their being able to make or find food and reproduce.

6–8: Evolution of Life

• Individual organisms with certain traits are more likely than others to survive and have offspring. Changes in environmental conditions can affect the survival of individual organisms and entire species.

USING THE STORy WITH GRADES K–4 With young children, you may have to explain the meaning of “hitchhikers.” You

might ask them to list the differences between animals and plants or to take the probe “Is It a Plant?” from Uncovering Student Ideas in Science, Volume 2 (Keeley, Eberle, and Tugel 2007). One of the differences they may mention is that plants do not move, while animals do. Since they may not yet be aware of the function of flowers in sexual reproduction, it might be useful for them to see that the fruits and vegetables they eat may have parts of the flower they came from attached to them if they pick them from the garden. Those in the store will probably have had them removed. I would strongly suggest that you use the term fruit when appropriate, even though children often mistakenly refer to the fruits of some plants as as seeds (e.g., dandelions, berries, milkweed, elm, maple, sycamore, and oak). Spring is a good time to take the children outdoors and let them begin to see the process from flower to fruit. If you have your students “adopt a tree” or other plant, they can observe it each day and watch the changes as the flower blooms, falls away, and leaves behind the fruit. You may also consider first using “Halloween Science,” another story in this volume (Chapter 15), in October, which focuses on pumpkins and their seeds, following up with this story in the spring, when they can view the flowers and see the fruits form.

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As usual, I like to start with a chart of “Our Best Thinking,” on what the children know about seeds. Most, if not all, students will be familiar with apple, orange, and grape seeds and cherry pits. Maybe they have noticed birds eating fruit from trees but do not realize that the seeds will be passing through the birds and landing elsewhere. They will, however, probably have seen dandelions and perhaps milkweed or willow fruits floating about in the air during spring and summer seasons. They may even have noticed the little helicopter fruits of the elm, sycamore, and maple trees. A good question for discussion might be: “What might be the value of seeds and fruits that fly away from the plants that produced them?” This can be followed by a discussion question like, “How can we find out what happens when too many plants try to live in the same spot?” Each year as we get ready to put our houseplants outdoors for their “summer vacation,” a great number of them need to be repotted into larger containers because they’ve added too many extra plants through the winter. Some plants thrive in the company of others of their species but many do not. Ask the children what happens when their little brother or sister invades their space. Do they need some room for themselves? Some plants do too, but perhaps for different reasons. Help the students design an investigation that will let them decide if certain plants do well when they are overcrowded. One way is to refer to the back of the seed packets (mustard or radish are good for this) and see if it suggests that the seeds be planted a certain distance apart. Here are some possible questions to ask: • What could be the reason for this suggestion? • What do you think would happen if you did not follow the directions and planted them much closer? • What do you think might happen if we put in 10 times the number of seeds suggested? • How would we compare them with those that are planted according to the directions? • What things do we need to measure as the plants grow? • What things do we need to keep the same in each pot? • What things do we need to keep the same in the way we care for the plants? After the investigation is over, the children should see that plants need space and the right amount of water and sunlight. Crowded plants are usually tall and spindly and unhealthy looking. This should lead students to see why it is an advantage for the seed to germinate away from the parent plant and not have to compete for the things it needs to be healthy. When this is completed, it is good to do a seed hunt to find out how the form and structure of the fruits they find help in avoiding crowding and overpopulation. If you are going to have a real seed hunt, the fall is a good time to arrange this. Acorns have fallen, burdocks are hitching rides, and milkweeds are flying. Fruits will vary from the large to the very small to the ones hidden inside melons and gourds. Don’t forget such fruits as apples, cherries, and raspberries. You would

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miss the maple, sycamore, and alder, which flutter down much earlier, but some of them are still lying around. (Or you can collect them in the spring and save them to demonstrate the winged fruits.) This is also the time to consider doing the story on “Halloween Science” (Chapter 14) in this volume, since pumpkin fruits are full of good science activities as well as seeds! This is a good time to demonstrate the connection between form and function. Children at this stage should be able to see that the form of any structure is related to the function it performs. The flying helicopters, the hooked hitchhikers, and the delicious fruits whose seeds pass through the animals’ intestinal tracts show examples of form and function—a major conceptual attainment. Children can make posters of the kinds of fruits featuring their forms and the way they distribute their seeds. Once they have realized that they are observing fruits, it will become easier to figure out how seeds are distributed because the structure of the fruits plays an important part in the distribution of the seeds.

USING THE STORy WITH GRADES 5–8 Children at this age will be anxious to get right out and find seeds. It will help them

in their search if you make them aware of the “form and function” concept before they go out. A chart of what they know about seed dispersal is the first step. If they are obviously mistaking fruits for seeds, you should clear up the misconception by merely stating that plant scientists (botanists) have decided to call the swelling of the ovary in a flower that protects the seed or seeds within after pollination the fruit. Have the students review their knowledge of plant parts and identify the pistil and stigma so that they can observe the swelling ovary of the pollinated flowers. You might ask them to list the ways that they think seeds are dispersed and why it is important for the seeds to travel a distance from their parents. Check out the questions in the previous section for ideas for inquiry into what happens when plants are crowded. Certain plants, such as lettuce, do not seem to show any adverse effects from crowding, but other plants, such as mustard, radish, and peas, are good choices for showing that plants that have to share resources with others in crowded conditions usually end up spindly and unhealthy. When you feel that they have enough information to go out and collect fruits and use their knowledge of form and function to classify the fruits’ dispersal methods, it is time for an assignment outside. If you can lead a field trip into the immediate area and find these fruits, this is a wonderful opportunity. If you cannot manage a field trip for one reason or another, give them a homework assignment to bring in examples of fruits, with any pertinent observational notes. With many different samples in front of them, students can do an in-depth observation and make drawings of each type of seed to classify them according to form and function. This should complete the questions associated with the story and the content standards.

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RELATED BOOKS AND JOURNAL ARTICLES Driver, R., A. Squires, P. Rushworth, and V. Wood-Robinson. 1994. Making sense

of secondary science: Research into children’s ideas. London and New York: Routledge Falmer. Keeley, P. 2005. Science curriculum topic study: Bridging the gap between standards and practice. Thousand Oaks, CA: Corwin Press. Keeley, P., F. Eberle, and C. Dorsey. 2008. Uncovering student ideas in science: Another 25 formative assessment probes, volume 3. Arlington, VA: NSTA Press. Keeley, P., F. Eberle, and L. Farrin. 2005. Uncovering student ideas in science: 25 formative assessment probes, volume 1. Arlington, VA: NSTA Press. Keeley, P., F. Eberle, and J. Tugel. 2007. Uncovering student ideas in science: 25 more formative assessment probes, volume 2. Arlington, VA: NSTA Press. Konicek-Moran, R. 2009. More everyday science mysteries. Arlington, VA: NSTA Press.

REFERENCES American Association for the Advancement of Science (AAAS).1993. Benchmarks for science literacy. New York: Oxford University Press. Keeley, P., F. Eberle, and J. Tugel. 2007. Uncovering student ideas in science: 25 more formative assessment probes, volume 2. Arlington, VA: NSTA Press. Konicek-Moran, R. 2008. Everyday science mysteries. Arlington, VA: NSTA Press. National Research Council (NRC). 1996. National science education standards. Washington, DC: National Academies Press.

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Chapter 15

Halloween Science

S

ella and her parents went out to the farmer’s market on a chilly October day to look for a pumpkin to make into a jack-o’lantern. They had several goals in mind. One was to find the best-looking pumpkin to carve for a decoration on Halloween. The second was to find a

pumpkin that would have the most seeds so that they could make salted pumpkin seeds for snacks. Sella and her family loved to eat pumpkin seeds and had a great recipe for making them. When they got to the market, pumpkins of all sizes and shapes surrounded them and the sight was overwhelming. How in the world would

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they find the perfect pumpkin? And how would they know which one had the most seeds? “I think the biggest pumpkin will have the most seeds. It makes perfect sense that the bigger the pumpkin, the more seeds it will have,” said Sella. “Look at the number of creases on the pumpkin, and that will tell you which one has more seeds,” said Dad. “I think the heaviest one will have the most seeds,” said Mom. “Because the heavier the pumpkin the more stuff is inside.” “But Mom, the heaviest will be the biggest, won’t it? And all that stuff inside isn’t just seeds, is it?” “Maybe not. Let’s lift up a few big and smaller ones and see,” said Dad. “And as for all the gunk inside, we’ll have to see what it’s used for. Maybe we can figure that when we open it up.” They ended up buying several pumpkins and taking them home to find out the answers to their questions. It turned out that when they began to work on the pumpkins, they had a lot more questions than they did at the market.

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PURPOSE Pumpkins are the perfect objects for inquiry since there are so many variations

among these fall fruits, yet there are some standard features of fruit that do not change among individuals. They are fun for children and adults alike, and probably one of the most popular yet most misunderstood of the fall fruits. This activity-based story should provide ample opportunities for students to engage in investigative science and answer most of their questions by direct observation. It should also sharpen their inquiry skills. There are many hidden connections to history, culture, and holidays as well. Many people will admit to spending more time picking out the best pumpkin than they do picking a holiday tree in December. When working with my undergraduates, mostly 21-year-olds, at least 20% said that they had never carved a jack-o’-lantern. How’s that for being culturally deprived?

RELATED CONCEPTS • Fruits and seeds • Variation • Measurement

• Estimation • Density • Scientific inquiry

DON’T BE SURPRISED Students may well have the usual “bigger is better” conception about comparing

different items. They may automatically assume that bigger pumpkins have more seeds and more ridges. This may be true, but they need the data to back it up. Their investigations will help them make a more informed decision.

CONTENT BACKGROUND The pumpkin is often thought of as a glorified squash. Indeed, it is a close relative,

being in the same family as cucumbers, gourds, squash, and melons, including watermelons. They all are in the family Cucurbitacea, and the Latin name of the pumpkin is Cucurbita pepo. They actually are a distinct kind of fruit, a special berry known as pepoes. If you think about it, all of the above mentioned fruits have lots of seeds inside the fleshy part and a hard rind on the outside. (Remember, in botanical terms, many of what we call vegetables are really fruits!) Inside the pumpkin is a multitude of seeds entangled in a mass of gunk, which is the most difficult part for the jack-o’-lantern maker. This gunk is part of what is known as the endocarp, the inner layer of the fleshy material is called the pericarp, which is what we eat. These stringy masses of flesh usually are full of moisture and feel quite slimy to the

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Chapter 15

person who dips their hands into the pumpkin to clean it out. However, it must be done and the reward for this is access to the wonderful seeds, which, when separated from the endocarp threads, can be roasted. They are a delicious addition to the fun of making the jack-o’-lantern. You might be able to see that some very thin strings are connected to the pointy ends of the seeds. These are probably the pollen tubes through which the pumpkin flower ovules were fertilized. They are very difficult to see, however, and may not be worth the trouble of finding them. The seeds are full of nourishment, including magnesium, phosphorus, zinc, iron, copper, protein, and vitamin K. There is some evidence that eating pumpkin seeds has some health benefits, such as lessening prostate enlargement, but this has not been scientifically verified. Besides this, they taste great as a snack, once toasted in the oven. There are viable seeds inside the pumpkin that can also be dried and planted. The number of seeds varies. Usually the larger pumpkins have the larger number of seeds and often the larger seeds. Some pumpkins are raised for size and exhibited at fairs. Some of these have weighed in at more than 1,000 pounds. For the local grower, however, smaller pumpkins averaging from 1–20 pounds are more profitable during the Halloween season, when the hollowed out fruits with carved faces and lighted candles inside grace the front porches and lawns of many North American homes. Although most recipes suggest using canned pumpkin flesh for making pumpkin desserts, the pumpkin itself can be used by peeling it, cutting up the pericarp or flesh, and cooking it. It is now of course the signature pie for Thanksgiving meals in the United States with unsubstantiated stories of how it was the dessert at the first Thanksgiving in Plymouth in 1621. It is an interesting fact that most canned pumpkin pie filling is made from Hubbard squash, which is sweeter than that of the ordinary pumpkin. Pumpkin flowers are monoecious (having separate male and female flowers on one plant) and are pollinated by bumblebees or honeybees. Since the pumpkin flowers do not have both male and female parts, their flowers are called imperfect. Flowers with both male and female parts are called perfect flowers. The male flower usually emerges first and the female flower slightly later. If the female flower is not pollinated, the flower falls off and no fruit results. One can recognize a pollinated flower as a swelling at the base of the female flower stalk. The flowers are only open for a short time during the day and may be closed by afternoon. They only remain open for pollination for a day or two, so the bees do not have much time to accomplish their task. Since pumpkin flowers do not self-pollinate, a great amount of variation among pumpkin fruit may show up in the next generation. The flowers are edible. The internet offers quite a few tasty recipes, from baked stuffed flowers to sautéed flowers in oil and garlic. This could present an interesting treat for a class studying pumpkins. As a historical aside, it is thought that the Irish brought the custom of carving fruits and making lanterns of them on All Hollow’s Day to the new world,

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but they were restricted to turnips since the pumpkin was not grown in Ireland. When they came to America, they were delighted to find the pumpkin to serve that purpose.

RELATED IDEAS FROM the NATIONAL SCIENCE EDUCATION STANDARDS (NRC 1996) K–4: Abilities Necessary to Do Scientific Inquiry • • • • •

Ask a question about objects, organisms, and events in the environment. Plan and conduct a simple investigation. Employ simple equipment and tools to gather data and extend the senses. Use data to construct a reasonable explanation. Communicate investigations and explanations.

K–4: The Characteristics of Organisms

• Organisms have basic needs. For example, animals need air, water, and food; plants require air, water, nutrients, and light. Organisms can survive only in environments in which their needs can be met. • The world has many different environments and distinct environments support the life of different types of organisms. • Each plant or animal has different structures that serve different functions in growth, survival, and reproduction.

K–4: Life Cycles of Organisms

• Plants and animals have life cycles that include being born, developing into adults, reproducing, and eventually dying. The details of this life cycle are different for different organisms. • Plants and animals closely resemble their parents.

5–8: Abilities Necessary to Do Scientific Inquiry • • • •

Identify questions that can be answered through scientific investigations. Design and conduct a scientific investigation. Use appropriate tools and techniques to gather, analyze, and interpret data. Think critically and logically to make the relationships between evidence and explanations.

5–8: Structure and Function in Living Systems

• Living systems at all levels of organization demonstrate the complementary nature of structure and function. Important levels of organization for structure and function include cells, organs, tissues, organ systems, whole organisms, and ecosystems.

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5–8: Reproduction and Heredity

• Reproduction is a characteristic of all living systems because no individual organism lives forever. Reproduction is essential to the continuation of every species. Some organisms reproduce asexually. Other organisms reproduce sexually.

5–8: Diversity and Adaptations of Organisms

• Millions of species of animals, plants, and microorganisms are alive today. Although different species might look dissimilar, the unity among organisms becomes apparent from an analysis of internal structures, the similarity of their chemical processes, and the evidence of common ancestry.

RELATED IDEAS FROM BENCHMARKS FOR SCIENCE LITERACY (AAAS 1993) K–2: Scientific Inquiry

• People can often learn about things around them by just observing those things carefully, but sometimes they can learn more by doing something to the things and noting what happens. • Describing things as accurately as possible is important in science because it enables people to compare observations with those of others. • When people give different descriptions of the same thing, it is usually a good idea to make some fresh observations instead of just arguing about who is right.

K–2: Diversity of Life

• Some animals and plants are alike in the way they look and in the things they do, and others are very different from one another. • Plants and animals have features that help them live in different environments.

3–5: Scientific Inquiry

• Results of scientific investigations are seldom exactly the same, but if the differences are large, it is important to try to figure out why. One reason for following directions carefully and for keeping records of one’s work is to provide information on what might have caused the differences. • Scientists do not pay much attention to claims about how something they know about works unless the claims are backed up with evidence that can be confirmed with a logical argument.

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3–5: Diversity of Life

• A great variety of kinds of living things can be sorted into groups in many ways using various features to decide which things belong in which group. • Features used for grouping depend on the purpose of the grouping.

6–8: Scientific Inquiry

• If more than one variable changes at the same time in an experiment, the outcome of the experiment may not be clearly attributable to any one of the variables. It may not always be possible to prevent outside variables from influencing the outcome of an investigation but collaboration among investigators can often lead to research designs that are able to deal with such situations.

6–8: Diversity of Life

• Animals and plants have a great variety of body plans and internal structures that contribute to their being able to make or find food and reproduce. • For sexually reproducing organisms, a species comprises all organisms that can mate with one another to produce fertile offspring.

USING THE STORy WITH GRADES K–4 If you like to combine reading and science, I can recommend an article by Karen

Ansberry and Emily Morgan (2008) called “Pumpkins” in Science and Children. They mention several trade books that are interesting reading for younger children and focus on some of the ideas involved in this story. For an inquiry-minded teacher, the pumpkin offers the ultimate in an object that provides a laboratory full of investigable questions. For the younger children, it provides a familiar object to investigate. It is important to have several pumpkins of different sizes for the children to study. Be frugal in your choice of pumpkins. We are often led to believe that bigger is better, but the smaller pumpkins (about head size or even slightly smaller) are easier to manipulate in the classroom and provide the same properties as the larger ones with less cost and fewer management problems. One large pumpkin might be usable just for comparison reasons, but children are much better off using the smaller ones. There are also pumpkin carving kits with safety knives that cannot harm small hands and are well worth the cost. The smaller pumpkins cause fewer problems when doing floating activities and are much easier to submerge for density and volume studies in the older grades. I usually start out by asking students what they already know about pumpkins and what they would like to know. They will have a great number of things to tell you about what they already know since they have probably been involved in some sort of family ritual involving a Halloween pumpkin. If you have children from other cultures in your classroom, you can find out if there are any traditions that

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Chapter 15

are comparable to ours, perhaps using pumpkins or other fruits on various holidays. This is particularly important if you have ELL students, since it gives them a chance to use their own experiences and encourages use of language. Some of your students may not have had any experience with pumpkins. This is a good time to have all students do an observation of the fruit and list all of the things that could be recorded. This might include size measurements, weight, number of seeds, number of vertical grooves, and the size and nature of the stem. In addition, you might ask them how they think a pumpkin is formed. It is a good idea to have a bathroom scale available since most pumpkins will not fit on the usual elementary balances. After they have listed the things they have observed, you can guide them into asking questions such as • • • • • • • • • • •

How do we find out which is the biggest pumpkin? Do we use weight or size to determine which pumpkin is biggest? How many seeds are in each pumpkin? Do the bigger pumpkins have more seeds? Do bigger pumpkins have bigger seeds? Do bigger pumpkins have more ridges than smaller ones? Does a pumpkin float? If it floats, does it float right side up? On its side? Upside down? Are the threads inside connected to the seeds? Where are the seeds located inside the pumpkin? How much does each pumpkin weigh?

Each of the above questions can be investigated directly by groups of students. After the seeds are taken out of the pumpkin and spread out on tables or desks, ask students to guess how many seeds they think their pumpkin had inside its body. This is strictly a guess for the fun of it. However, when answering the other questions, students should give a reason for their hypotheses. You also have an opportunity to teach a little lesson on estimation. Once the seeds are taken out of the pumpkin, washed and separated from the strings, and laid out on a newspaper on the tables or desks, ask the students if there are ways they can estimate the number of seeds without counting each one. You may want to introduce your younger students to counting by tens, fives, twos, or whatever number groups you are studying. If the seeds are laid out in groups, you can help them find out how many seeds there are in total. Some students may actually find ways of estimating the number of seeds using techniques you have not thought of. If the students are doubtful about the results, you may have them count the seeds one by one to see how accurate the estimating was. In a scientific lab, this technique is called quality control. It is used in bacteriology labs to check on the accuracy of counts of microbial colonies on petri dishes. Technicians often develop different ways to estimate the colonies and then do quality control checks on how accurate the estimations have been.

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When the seeds are cleaned and dried, you can find many different recipes for baking the seeds to use as snacks. Knowing your students’ possible dietary restrictions will guide you in which recipe to use. Some seeds can be saved from the oven and planted. They produce two seed leaves because they are dicotyledons, meaning they will produce two leaves when they germinate. Watching the new cycle begin again is often an exciting experience for young children, especially since by then they have built a lasting and sometimes loving relationship with the pumpkin.

USING THE STORy WITH GRADES 5–8 I like to start with one of my favorite pumpkin activities for older students. It is called

“Pumpkin π” (or “Pumpkin Pi”). Break your students into groups, each group with a pumpkin, and before doing anything else, direct them to measure the circumference of the pumpkin and find a way to measure the diameter. Create a chart on the front board or on a sheet of easel paper. Make cells to contain data on the circumference of the pumpkins, the diameter of the pumpkins, and the circumference divided by the diameter. Each group of students doing the measurements and calculations on their own pumpkins should record their results in the cells for all of the class to see. The end calculation will always come out to approximately the value of π. Many students have used π in formulas without realizing where the value came from. Even adults have told me that they thought pi was some magic number. Any circle, paper plate, bicycle wheel, or circular wastebasket will give the value of π if the circumference is divided by the diameter. The pumpkin pi in this activity is a mnemonic that will help the students remember the relationship for a long time. Middle school students are capable of using a great deal of mathematics in this activity. They can determine the volume of the pumpkins by water displacement. I have found that placing a wastebasket filled to the brim with water in a larger container is a good setup for the water displacement for volume activity. The water that spills over is the amount of water the pumpkin displaced and therefore the volume of the entire pumpkin. You will have to push the pumpkin under the water with a fork or other tool since the pumpkin will float. The spilled water is then transferred to a measuring container. Students usually want to do the same with an empty pumpkin to see how much water the pumpkin can hold. Pouring water into the empty pumpkin, then measuring that amount, can do this. Before you continue on with density and buoyancy, a little refresher may be in order. The density of the opened and cleaned pumpkin is quite different from that of one that has not been opened. First of all, once water has filled the hollowed-out space of the pumpkin, the amount of water that the shell of the pumpkin displaces will be much lower this time, as the water will first fill in the hollow part of the pumpkin. You will merely be measuring the volume of the shell of the pumpkin. Warn your students to be sure to put the pumpkin into the water on its side very carefully, so as not to allow any water to spill out of the container until the entire pumpkin can be submerged. They will notice that much less water spills over into

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the container from the wastebasket and that the density of the pumpkin flesh alone is much less. This may evoke a discussion as to why this is so and the concept of density will be further rooted in experience. Ask the students if they feel the difference in upward force between submerging the intact pumpkin and the opened pumpkin. Ask them to notice if the open pumpkin floats higher or lower than the intact pumpkin. Students may also want to use the formula, Density = Mass/ Volume to see if all parts of the pumpkin have the same density. There are other questions that might be investigated, and even if the students do not bring them up, you may want to ask the following: • • • • • • • • • •

Are the seeds arranged randomly or in a pattern? Are the strings that are attached to the seeds attached to the wall of the pumpkin? Is there a relationship between the ridges and the seed connections? Are there more creases on bigger pumpkins than on smaller ones? Are there more seeds in pumpkins that have more creases? Do more creases mean more seeds in a pumpkin? Are all of the seeds in a pumpkin the same size? If not, is there a place where you can find bigger or smaller seeds? Dismantle the pumpkin and find out which parts float and sink. If pumpkins float, do smaller pumpkins float higher or lower than bigger pumpkins? • If you soak a pumpkin seed overnight, can you find a small plant inside? How about soaking it for two nights? If you would like to see additional ideas of things to explore on pumpkins, see the article “Assessment With Pumpkins,” by Erin Sykes and Donna Sterling (2006) in Science Scope. This article focuses on middle school activities involving measurement and observation of pumpkins.

RELATED BOOKS AND JOURNAL ARTICLES Driver, R., A. Squires, P. Rushworth, and V. Wood-Robinson. 1994. Making

sense of secondary science: Research into children’s ideas. London and New York: Routledge Falmer. Keeley, P. 2005. Science curriculum topic study: Bridging the gap between standards and practice. Thousand Oaks, CA: Corwin Press. Keeley, P., F. Eberle, and C. Dorsey. 2008. Uncovering student ideas in science: Another 25 formative assessment probes, volume 3. Arlington, VA: NSTA Press. Keeley, P., F. Eberle, and L. Farrin. 2005. Uncovering student ideas in science: 25 formative assessment probes, volume 1. Arlington, VA: NSTA Press. Keeley, P., F. Eberle, and J. Tugel. 2007. Uncovering student ideas in science: 25 more formative assessment probes, volume 2. Arlington, VA: NSTA Press.

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Konicek-Moran, R. 2008. Everyday science mysteries. Arlington, VA: NSTA Press. Konicek-Moran, R. 2009. More everyday science mysteries. Arlington, VA: NSTA Press.

REFERENCES American Association for the Advancement of Science (AAAS).1993. Benchmarks for science literacy. New York: Oxford University Press. Ansberry, K., and E. Morgan. 2008. Pumpkins. Science and Children 46 (2): 18–20. National Research Council (NRC). 1996. National science education standards. Washington, DC: National Academies Press. Sykes, E., and D. Sterling. 2006. Assessment with pumpkins. Science Scope 30 (2): 25–29.

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Chapter 16

In a Heartbeat

T

hump! Thump! Thump! Ryan’s heart felt like it was going to explode in his chest. He had just run a mile around the city with his brother who jogged every morning. “Hey little bro,” said Tom. “You look like you’re really out of shape! Guess you’re not getting enough exercise. Come out with me every morning and we’ll have you ready for a marathon in no time.”

Ryan gulped some air and sat down on the curb as his heart slowed down to a softer beat. “Here, let me take your pulse,” said Tom as he took hold of Ryan’s arm. “Leggo man!” said Ryan as he tried to jerk his arm away. He was in no mood for the big brother stuff, but he was too tired to resist so he let Tom put his fingers on his wrist. “Boy, your heart is really racing!” said Tom.

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“What? You can count my heartbeats in my arm?” Ryan exclaimed weakly. “Sure, when your heart pumps, it sends blood through your blood vessels, and in lots of places on your body you can feel that pumping. Haven’t you ever been to a doctor?” “Well sure, but they’re poking me and everything all over and I don’t know what they’re doing half the time. Anyway, does my heart pump the blood the same number of beats in all these places?” “Sure. I think so, why not? What the heck, I’m no doctor. Maybe they don’t. Haven’t Mom and Dad ever taken your pulse?” “Mom might have, but only when I was sick,” replied Ryan. “And then she feels my forehead and takes my temperature.” “Well, that’s to see if your heart rate is up. It tells if you’re sick.” “Am I sick now?” asked Ryan. “Nah! You’ve just been exercising.” “Wait a minute. My heart beats faster when I’m sick and when I exercise? That’s weird. How does my heart know the difference?” “Your heart doesn’t know anything,” said Tom. “It just does what your body needs it to do.” “What other things make my heart beat faster or slower, Tommy?” asked Ryan. “Not sure,” admitted Tom, walking away. “And don’t call me Tommy!” “Okay, how can I make my heart beat faster or slower? Does it change during the day? How about when I get older?” Ryan called after his brother excitedly. “Whoa, little brother, chill out! I think we can get some answers. Come here and I’ll show you how to take your pulse and you can find out for yourself. Then you can tell me.”

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PURPOSE All children are interested in how their bodies work. This story is aimed at helping them discover what kinds of activities change their heart rate. It also is a steppingstone into learning more about the circulatory system and how it works within the human body.

RELATED CONCEPTS • Blood • Blood cells • Health and exercise

• Lungs • Respiration • Circulatory system

DON’T BE SURPRISED Most children have had their pulse taken by a parent or doctor or nurse. They may

not be aware of exactly what is happening or why that vital sign is important. They know that if they complain of not feeling well, their caregiver will often take their pulse before doing anything else. They will probably not be aware that it is not only a measurement of the rate of heartbeat but also of heart strength and rhythm. Many children will not have an understanding of the network of heart, veins, arteries, and capillaries, and its relationship to body function. Some students may also still believe the stories and love songs about broken hearts or emotions being stored in the heart. They may also believe that the shape of the heart is like a valentine.

CONTENT BACKGROUND A circulatory system is vital to many animals because it carries gases, hormones,

and nutrients to various parts of their bodies. It takes waste products produced in cellular respiration from cells and brings them to organs that remove waste. Vertebrates (animals with backbones) have what is known as a closed circulatory system. That means that, short of injuries, the circulating blood does not leave the confines of the arteries, veins, and capillaries. Some invertebrates (animals without backbones) have open circulatory systems in which blood flows out of the heart and returns by flowing back through the open body chamber. Polychaete worms (mostly marine worms) are the exception. A word about systems: We use the term system often but it is important to be specific about what we mean. A system is any collection of objects or ideas that have an influence on each other and on an associated group. A system can range from a bicycle (a machine) to a collection of living things in an environment (ecosystem). We talk of solar systems, weather systems, and in this particular story, a collection of

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organs called a circulatory system. Governments are made up of systems, and mathematics has systems such as theorems or equations. Some systems are so large we break them down into subsystems. For example, a bicycle has several subsystems that make up the whole, such as gear systems, steering systems, and propulsion systems. If you change any one part of a system or subsystem, it affects all parts of the system and connected systems. It is also important to view systems such as the circulatory system as a part of the whole human body system. Thus when anxiety or infection affects any part of the body, it impacts the circulatory system and all other systems that make up the larger system. In short, no system within a larger system is independent of any of the other parts. This is particularly important to remember when you are talking about the pulse and heart rate as we are in this story. If you decide to enter into a discourse on systems and their importance in science, you might want to give your students the probe “Is It a System?” found in volume 4 of Uncovering Student Ideas in Science (Keeley and Tugel 2009). The human circulatory system on which we focus in this story is made up of the heart (the pump), the arteries, capillaries, and veins that control the flow of the blood as it circulates through our bodies. Basically, the heart pumps the approximately 10.6 pints of blood (5-plus liters) in the adult body through a series of flexible tubes (veins, arteries, and capillaries) to all parts of the body. The heart is about the size of a fist and is located just to the left of the center of the chest. Blood is a fluid (plasma) containing red and white blood cells, platelets, dissolved oxygen and carbon dioxide, nutrients, and waste products. Plasma is mostly water with some amounts of dissolved salts. The red cells carry oxygen and carbon dioxide; the white cells fight infections; and the platelets help the blood clot when the body is injured. What the blood carries at any given place in the body depends on whether it is traveling away from or back to the heart and lungs. We can feel our pulse because the heart pumps blood through the arteries in a rhythmic pattern. Where the arteries are near the surface of the skin, we can feel it as the artery expands. Normally, the heart pumps between 60 and 100 beats per minute (bpm) for adults to 120 bpm for newborns. The bpm varies with fitness, age, and genetics. The only way to determine normal bpm for any individual is to test it over time in a resting position, when the person is not suffering from an infection. This is called a baseline heart rate. Heart rates taken at any other time are compared to this. Long distance runners can have baseline heart rates at about 40 bpm. An increase in bpm can be caused by anxiety, dehydration, exercise, eating, and infection. As a child in the 1930s, during what is now known as the polio anxiety period, I remember having my pulse taken often by a worried parent. They’d thrust a thermometer beneath my tongue for what seemed like hours—but was actually only three minutes. A high temperature and pulse rate would result in a doctor appearing at our door. (Yes, there were times in our history when doctors made house calls!) Usually the first thing he did was take my pulse. The human heart is a four-chambered muscular pump that beats billions of times in an average lifetime and never stops for a rest. It has evolved into a marvel of efficiency for distributing blood throughout the body. Its muscle, the myocardium,

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found nowhere else in the body, has its own electrical pacemaker that receives messages from the brain to set the rhythm and the rate of the heart. When this pacemaker fails to do its duty correctly, an artificial pacemaker may be inserted. The four-chambered heart takes in blood that has been distributing nutrients and collecting waste from around the body and sends it to the lungs for a transfer of carbon dioxide (waste gas) for oxygen. The now oxygenated blood returns to the heart and is pumped out to the body. The oxygen is transferred to the cells and used in cellular respiration. As the blood passes through the body, it distributes much-needed nutrients and gases through the capillaries—thin-walled, tiny ducts that allow the nutrients to ooze out into the surrounding tissues. Here also the blood picks up waste materials, which are delivered to the kidneys (and then to the bladder) for collection and elimination; and it gathers excess carbon dioxide to be exchanged for oxygen in the lungs. Thus the cycle is repeated. Below is a diagram of the heart’s four chambers. Note that the carbon dioxide– rich blood enters the right atrium, is then pumped into the right ventricle and from there to the lungs. Oxygenated blood returns to the left atrium, is then pumped .

Aorta Pulmonary artery

Pulmonary artery

Pulmonary veins Pulmonary veins

Left atrium Left ventricle

Right atrium

Right ventricle

Vena cava Aorta

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into the left ventricle, and from there goes out to the body via the largest artery, the aorta. The left ventricle pumps with exceptional force and is the source of the pulse that is found in many parts of the body. The left side of the heart is involved in pumping oxygenated blood and the right side in pumping deoxygenated blood. Since it is responsible for pumping blood throughout the entire body, the left side is more muscular. Between the chambers are one-way valves that do not allow blood to backflow. When you hear heart sounds through a stethoscope, what you hear are the valves closing. Sometimes because of birth defects or injury, these valves do not work properly and leak. These may have to be repaired through surgery if the leaks are bad enough to cause problems. The heart muscle is also fed by its own supply of blood vessels that need to be healthy for the heart to function properly. These vessels and the heart are called the coronary system. Bad diet, including too much saturated fat, may cause some of these to clog. The part of the heart that is serviced by these vessels can be injured to the point where heart muscle cells die ffrom lack of blood. This is often what is called a heart attack. Most of the habits that are harmful to the heart can be avoided by being aware that obesity, drug usage, smoking, and untreated body infections can affect the health of the heart. Since heart disease is the number one killer in our society, it is not too early to help children know about the things that promote good health and prevent heart disease. Bad habits that affect the heart start at an early age, so we should teach our children healthy ones.

RELATED IDEAS FROM the NATIONAL SCIENCE EDUCATION STANDARDS (NRC 1996) K–4: The Characteristics of Organisms

• Organisms have basic needs. For example, animals need air, water, and food; plants require air, water, nutrients, and light. • Organisms can survive only in environments in which their needs can be met.

5–8: Structures and Function in Living Systems

• Living systems at all levels of organization demonstrate the complementary nature of structure and function. Important levels of organization for structure and function include cells, organs, tissues, organ systems, whole organisms, and ecosystems. • All organisms are composed of cells—the fundamental unit of life. Most organisms are single cells; other organisms, including humans, are multicellular. • Specialized cells perform specialized functions in multicellular organisms. Groups of specialized cells cooperate to form a tissue, such as a muscle. Different tissues are in turn grouped together to form larger functional units,

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called organs. Each type of cell, tissue, and organ has a distinct structure and set of functions that serve the organism as a whole. • The human organism has systems for digestion, respiration, reproduction, circulation, excretion, movement, control and coordination, and for protection from disease. These systems interact with one another.

RELATED IDEAS FROM BENCHMARKS FOR SCIENCE LITERACY (AAAS 1993) K–2: Basic Functions

• The human body has parts that help it seek, find, and take in food when it feels hunger—eyes and noses for detecting food, legs to get to it, arms to carry it away, and a mouth to eat it. • The brain enables human beings to think and sends messages to other body parts to help them work properly.

3–5: Basic Functions

• From food, people obtain energy and materials for body repair and growth. The indigestible parts of food are eliminated. • By breathing, people take in the oxygen they need to live. • The brain gets signals from all parts of the body telling what is going on there. The brain also sends signals to parts of the body to influence what they do.

6–8: Basic Functions

• Organs and organ systems are composed of cells and help to provide all cells with basic needs. • For the body to use food for energy and building materials, the food must first be digested into molecules that are absorbed and transported to cells. • To burn food for the release of energy stored in it, oxygen must be supplied to cells, and carbon dioxide removed. Lungs take in oxygen for the combustion of food and they eliminate the carbon dioxide produced. The urinary system disposes of dissolved waste molecules, the intestinal tract removes solid wastes, and the skin and lungs rid the body of heat energy. The circulatory system moves all these substances to or from cells where they are needed or produced, responding to changing demands.

USING THE STORy WITH GRADES K–4 Even the youngest children will have had the experience of having had their pulse

taken. They may not know why, but they know that it is usually done when they complain of feeling ill. As was suggested in the story, it is important for them to

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Chapter 16

know that the heart rate can change for reasons other than illness, that the heart is part of a much larger system, and one of many systems in the human body. As is the usual custom, I start by finding out what children know about the heart, where it is, what it does, and how they can be aware of how fast it is beating. I then write these on chart paper. If possible, the statements are changed to questions that can be investigated. I show them how to take their pulse on the carotid artery in the neck, the easiest one to find. I let them feel mine and then try to find it on themselves. If they can count to 20, it is usually enough to have them take a pulse for 15 seconds. If they can add, they can add that number four times; or if they can multiply they can multiply by 4 since 15 seconds is ¼th of a minute. We need to explain to them that   1. Superficial temporal beats per minute is the standard. There   2. External maxilary is quite an opportunity for integrating   3. Carotid math and science here, especially if the   4. Brachial curricula match. I always find that if the   5. Ulnar children care about the answers to math   6. Radial problems, they learn better.   7. Femoral I ask them to predict (with a reason)   8. Popliteal what kinds of things will make their   9. Posterior tibial heart beat faster or slower. They usually 10. Dorsalis pedis 7 come up with some of the following:

1 2 3

4

6 5

• • • • • •

8

10

9

Exercising makes your heart beat faster. Eating makes your heart beat faster. Clapping or running in place makes your heart beat faster. Standing up makes your heart beat faster. Lying down makes your heart beat slower. Being scared makes your heart beat faster.

After these predictions have been changed into questions, they have to choose a place to count their pulse or the pulse of a partner. I usually start with the radial pulse in the wrist or the carotid pulse in the neck. After students have learned to take the radial (wrist) pulse, ask them to find other places on their bodies where they can feel a pulse. I find one on myself that is not often listed and that is at the base of the thumb on the palm. Other places are the carotid in the neck, the temporal at the temple, the brachial in the upper arm or on the inside of the elbow, the radial on the wrist, the ulnar just above the wrist, the femoral in the groin, the popliteal behind the knee, the dorsalis pedis on the instep, and the posterior tibial, just below the ankle bone. Obviously some of these are not very convenient and are not as strong as others. The favorites of many health professionals are the carotid and the radial. When you have your blood pressure taken, the health provider usually places the stethoscope over the brachial, on the inside surface of the elbow joint.

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Caution here! Find out if any of your students have health problems that rule out exercise if they choose that particular investigation. Results will vary but you can be certain that any sustained movement will result in an increase in pulse rate. Eating usually does the same for most subjects. Taking a resting pulse before and after lunch can be accomplished quite easily. These can be graphed and published on the bulletin boards. And the original chart of prior knowledge about the heartbeat can be modified as appropriate.

USING THE STORy WITH GRADES 5–8 You’d think that older students would be much savvier about the heart and pulse.

You might be surprised. It is best to begin by finding out just what they think about the heart and circulatory system as suggested in the previous section. Their investigation questions may be a bit more sophisticated such as • Do the pulses at the extremities of the body beat at the same time as the ones closer to the heart? • Are pulses at different points in the body the same in rate? • If you are running, is your leg pulse faster than the others? • Can you feel a pulse in a vein? Why or why not? • Can meditation be used to change your heartbeat rate? • What is biofeedback? • Does biofeedback work? • How does biofeedback work? • How do other animals with hearts circulate their blood? • Does the outside temperature affect your heart rate? • Does heart rate change with age? Sometimes we get questions like “Do those energy drinks really work?” There might be a question about whether those energy drinks raise your heart rate. Obviously, this is not a test for in school, but if they know of someone who does drink them, they could conduct a test outside of school. The same thing could be true of drinking coffee. I know of a school that encourages this type of inquiry and has a policy of trying to develop a schoolwide project about important topics. This would probably be of interest to the entire school, including the administration and PTA. Your students could conduct a study by going room to room to see if the average heart rate is different at each grade level. The results could be posted in an area of the school where visitors or other students could view the data. Many teachers of lower grades welcome this kind of inter-age research. It would take time for you to prepare your students on how to either instruct younger students in taking their pulses or to actually conduct the study themselves, but the activity would be worth it in the long run.

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No matter what question or questions your students decide to follow, their understanding of the circulatory system, the human body, and the nature of science should increase.

RELATED BOOKS AND JOURNAL ARTICLES Driver, R., A. Squires, P. Rushworth, and V. Wood-Robinson. 1994. Making sense

of secondary science: Research into children’s ideas. London and New York: Routledge Falmer. Keeley, P. 2005. Science curriculum topic study: Bridging the gap between standards and practice. Thousand Oaks, CA: Corwin Press. Keeley, P., F. Eberle, and C. Dorsey. 2008. Uncovering student ideas in science: Another 25 formative assessment probes, volume 3. Arlington, VA: NSTA Press. Keeley, P., F. Eberle, and L. Farrin. 2005. Uncovering student ideas in science: 25 formative assessment probes, volume 1. Arlington, VA: NSTA Press. Keeley, P., F. Eberle, and J. Tugel. 2007. Uncovering student ideas in science: 25 more formative assessment probes, volume 2. Arlington, VA: NSTA Press. Konicek-Moran, R. 2008. Everyday science mysteries. Arlington, VA: NSTA Press. Konicek-Moran, R. 2009. More everyday science mysteries. Arlington, VA: NSTA Press.

REFERENCES American Association for the Advancement of Science (AAAS).1993. Benchmarks for science literacy. New York: Oxford University Press. Keeley, P., and J. Tugel. 2009. Uncovering student ideas in science: 25 new formative assessment probes, volume 4. Arlington, VA: NSTA Press. National Research Council (NRC). 1996. National science education standards. Washington, DC: National Academies Press.

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Chapter 17

The Trouble With Bubble gum

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S

hanti loved chewing gum. He knew it was not allowed in a lot of places, but he still loved it anyway. His mom insisted on the sugarless kind of gum, and so did his dentist, but every once in a while, he cheated a little bit. Actually, he cheated more than a little bit. When it came to bubble gum, Shanti was hooked on the sugar kind. Not only was the flavor wonderful, but he had so much fun making the bubbles and letting them break all over his face. And, once in a while it couldn’t hurt, could it? “What’s so bad about bubble gum?” Shanti thought. Some kids would chew three or four pieces at a time. He couldn’t figure out how they did that. It seemed to swell up in his mouth and was like trying to eat a whole hamburger in one bite. When the flavor was gone and he got tired of blowing bubbles, he had to get rid of it. A piece of used bubble gum looked like it could choke a horse. “It must gain weight when you chew it. Saliva and stuff must get into it,” thought Shanti. “Does gum get heavier when you chew it?” Shanti asked his friends whose mouths were so full they looked like chipmunks. “That’s for sure!” said one, his mouth so full you could hardly understand him. He was a three-piece chewer. “Nah,” said another, who was evidently a one-piece chewer. “Stays the same,” said others, examining their chewed wads carefully. “One way to find out,” said Shanti. And they did. And what they found amazed everyone. “Wow, who would have thought that?” said Shanti. “And I wonder if it is true for all kinds of gum?”

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PURPOSE Bubble gum (and chewing gum, for that matter) has become a minor anathema to

teachers and parents, not to mention dentists, although the latter pretty much agree that nonstick, sugarless gum chewed after meals helps prevent cavities. But we are talking about bubble gum here, a whole different story. We are concerned with finding out what happens to the weight of the gum when it is chewed, which leads to concepts of food absorption and nutrition, and with helping children understand what is so “bad” about bubble gum, which is part of learning about oral hygiene. Designing a good investigation into whether gum loses weight, gains weight, or stays the same after chewing is another one of the purposes of the story. I am indebted to the people at AIMS (Activities for Integrating Math and Science) Education Foundation for the idea that led to this story and for all of the fun I have had doing this activity with so many kids over the years (AIMS 2006).

RELATED CONCEPTS • Sugar • Oral hygiene

• Cavities and bacteria • Experimental design and scientific inquiry

DON’T BE SURPRISED Most students are totally unaware of the amount of sugar in bubble gum and don’t know that they are literally eating sugar in huge amounts. They normally predict that the gum will gain weight due to the addition of saliva. Further, they are probably unaware that sugar provides the fuel for oral bacteria and can increase the frequency of cavities big time! They may also have difficulty figuring out how to design a fair investigation to solve the mystery.

CONTENT BACKGROUND Does your chewing gum lose its flavor on the bedpost overnight? If your mother says don’t chew it, should you swallow it in spite? The above lines are from a popular song from 1958, demonstrating that this delightful but sometimes annoying habit has been around a long time. Our neolithic ancestors used to chew resin from pines, as did our more recent pioneers. That is, until chicle—a natural gum from a tropical evergreen tree—was imported from Mexico as a rubber substitute in the late 1800s and finally made its way into chewing gum because it was softer and held its flavor longer.

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What is the flavor that is so addictive to bubble gum chewers? Why, it is sugar, of course. It comes in all forms: corn syrup, cane sugar, rice sugar, and sugar flavorings. Most of the flavoring of sugarless gum is in the form of sugar substitutes (saccharin, aspartame, or sorbitol). North American kids spend about half a billion dollars on bubble gum each year! One interesting fact: Bubble gum forms the best bubbles when the sugar is gone. Where does it go? I think you can figure that one out on your own. But that is the big answer to the mystery in the story. Students will learn that somewhere around 60–75% of the weight of the gum disappears into the body of the chewer after 10 minutes of chewing (sugarless gum loses less). I can guarantee you that they will be amazed!

RELATED IDEAS FROM the NATIONAL SCIENCE EDUCATION STANDARDS (NRC 1996) K–4: Abilities Necessary to Do Scientific Inquiry • • • • •

Ask a question about objects, organisms, and events in the environment. Plan and conduct a simple investigation. Employ simple equipment and tools to gather data and extend the senses. Use data to construct a reasonable explanation. Communicate investigations and explanations.

5–8: Abilities Necessary to Do Scientific Inquiry • • • •

Identify questions that can be answered through scientific investigations. Design and conduct a scientific investigation. Use appropriate tools and techniques to gather, analyze, and interpret data. Think critically and logically to make the relationships between evidence and explanations.

K–4: Personal Health

• Individuals have some responsibility for their own health. Students should engage in personal care—dental hygiene, cleanliness, and exercise—that will maintain and improve health. Understandings include how communicable diseases, such as colds are transmitted and some of the body’s defense mechanisms that prevent or overcome illness. • Nutrition is essential to health. Students should understand how the body uses food and how various foods contribute to health. Recommendations for good nutrition include eating a variety of foods, eating less sugar, and eating less fat. • Different substances can damage the body and how it functions.

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6–8: Personal Health

• Food provides energy and nutrients for growth and development. Nutrition requirements vary with body weight, age, sex, activity, and body functioning.

RELATED IDEAS FROM BENCHMARKS FOR SCIENCE LITERACY (AAAS 1993) K–2: Scientific Inquiry

• People can often learn about things around them by just observing those things carefully, but sometimes they can learn more by doing something to the things and noting what happens. • Describing things as accurately as possible is important in science because it enables people to compare their observations with those of others. • When people give different descriptions of the same thing, it is usually a good idea to make some fresh observations instead of just arguing about who is right.

3–5: Scientific Inquiry

• Results of scientific investigations are seldom exactly the same, but if the differences are large, it is important to figure out why. One reason for following directions carefully and for keeping records of one’s work is to provide information on what might have caused the differences.

6–8: Scientific Inquiry

• If more than one variable changes at the same time in an experiment, the outcome of the experiment may not be clearly attributable to any one of the variables. It may not always be possible to prevent outside variables from influencing the outcome of an investigation, but collaboration among investigators can often lead to research designs that are able to deal with such situations.

K–2: Physical Health

• Eating a variety of healthful foods and getting enough exercise and rest help people to stay healthy. • Some things people take into their bodies from the environment can hurt them.

3–5: Physical Health

• Food provides energy and materials for growth and repair of body parts. Vitamins and minerals present in small amounts in foods are essential to keep everything working well. As people grow up, the amounts and kinds of food and exercise needed by the body may change.

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6–8: Physical Health

• The amount of food energy (calories) a person requires varies with body weight, age, sex, activity level, and natural body efficiency. • Toxic substances, some dietary habits, and personal behavior may be bad for one’s health. Some effects show up right away, others may not show up for many years. Avoiding toxic substances, such as tobacco, and changing dietary habits to reduce the intake of such things as animal fat increases the chances of living longer.

USING THE STORy WITH GRADES K–4 Kids love this activity. Not only do they get to chew gum in school, but the teacher

is asking them to do so! No other motivation is needed! Without much coaching, the children soon realize that there is only one way to solve this problem. However, you will want to help them decide if they are going to choose just one kind of gum or several. You will also certainly need to find out from parents if there are any health restrictions or any other reason why a child might not be able to participate. You can let the parents know that you will be providing sugarless gum so that their child can still participate if sugar is the only problem. This activity is one that is easily integrated with math and graphing—specifically with histograms. I ask each child to predict one of three choices: weight loss, weight gain, or weight stays the same. Each child has a small square of paper that they tape to a graph on a large sheet of paper that has the three choices along the bottom of the graph and numbers on the left-hand vertical line. Each child stands, makes a prediction and explains it, and places the square on the graph, creating a histogram of predictions. This also ensures that each child has an investment in the prediction and the activity. In grade 2 and up, children can begin to design the investigation. (K–1 children may be a little young for coming up with an experimental design, but are probably able to do the investigation under your instruction. All they need to know is how to count.) If groups of children work together then report back to the class before starting the procedure, there is ample opportunity to help them make sure they have controlled for variables and that the design has no flaws. Group work also has another value and that is that gum is best weighed as packs, usually five pieces, since weight loss is more dramatic and less prone to measurement errors than if students use single pieces of gum. Be sure to have each group save the packaging so that you can review the ingredients later. I suggest that you use balances and gram weights. This is another reason for using five pieces of gum rather than one because of the limited accuracy of the simple classroom balances. If you use interlocking gram pieces such as Centicubes, you can lock them together when you have finished measuring the weight of the gum, before and after. These become a three-dimensional graph to complement

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the graph that you can create on the board. This is especially important for younger children because they can move from the concrete to the abstract by comparing their cube graphs with the symbolic graph on the board. Children usually decide to weigh the gum in their individual wrappers for sanitary reasons, and then record the weight of the unchewed gum, both in their notebooks and on the classroom graph. If different brands of gum are used, there should be separate columns for each brand. One of the children from each team can again use little squares of paper, each representing a gram, to paste to the classroom graph. There may be some discussion about whether or not weighing the paper along with the gum will affect the results. That’s good, because with younger children, the more discourse on a topic such as this, the closer to understanding the concept of taring—determining a fair weight, including extraneous objects such as containers or wrappers. Students may soon see that as long as the same wrappers are used before and after, the result will be the same. They may have had experiences with watching a salesperson weigh something at a market and wonder about the weight of the paper or tray it is weighed upon. (Note: Either it is considered negligible or the scale has been set to tare the weight of the tray.) The children usually decide that everyone should chew a piece of gum for the same length of time. You may want to suggest 10 minutes as an arbitrary goal. You should impress on the children that they all need to start at the same time since, in my experience, they are apt to begin to chew as soon as the weighing is completed. They may also have to be reminded to save the wrapper for the reweighing. You may want to have them do something else during the chewing for the time to go faster. Then, each child should put his or her gum into the paper wrapper in which it was weighed before chewing, and all five pieces should be weighed and recorded together. When the results in numerical and graphic form are compared, the children are almost always amazed to see the amount of weight loss. If you have used interlocking gram pieces, the comparison of the two may not be numerical, but it will be obvious that the difference is huge. For your older students, you can use the math that is appropriate for your class when you analyze the results. Next, you or the children may ask, “Where did the weight go?” You can ask if the flavor is gone or at least not as strong. A look at the label will tell the children what was in the gum. You may have to introduce them to what the terms corn syrup and other synonyms for sugar mean for their nutrition. I remember that many children said to me after the activity, “Now I know why I’m not supposed to chew a lot of bubble gum.” You will notice that there is no promise to abstain, but at least there is the knowledge.

USING THE STORy WITH GRADES 5–8 The techniques for these grade levels are similar to those mentioned above except that your students may be more sophisticated in the use of balances and can be

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Chapter 17

more accurate using triple-beam balances or electronic scales. They will have less trouble designing the investigation, but the result will be just as surprising as with younger children. I have used this activity with college seniors and found that they are no less excited to do it and no less amazed at the results. Please read the above grade-level section and see how those ideas fit in with your students. For children in grades 5–8 calculating the percentage of loss should be no problem, and the exercise allows you the opportunity to give children a reason for doing math. A girl once said to me that math was “pages and pages of other people’s problems.” With activities like these, children own the problems, and the calculations to find the answers have more meaning for them. For more of these types of activities for integrating science and math, I recommend that you look into the books produced by the AIMS Education Foundation (www.aimsedu.org). They are arranged so that you can find a math activity that leads into or supports the math needed for your science activities or vice versa. Additional questions may arise as to what would happen to the results if the gum were to be chewed for 20 minutes instead of 10, for example, leading to a host of other investigations. You also have an opportunity to teach children how to read food labels. Ingredients are listed in amount order, with the greatest first, leading down to the least. Reading cereal boxes and other commonly eaten snack foods can be very enlightening. A visit to the grocery store is a wonderful field trip, particularly if you have them focus on the cereal aisle. Not only is the reading of the labels instructive, but the placement of the “Mommy, can I have this one?” cereals at kid eye level is pretty obvious. Hereby lies a lesson in marketing. You seldom find high fiber and healthier cereals on a level that small children can see.

RELATED BOOKS AND JOURNAL ARTICLES Driver, R., A. Squires, P. Rushworth, and V. Wood-Robinson. 1994. Making sense

of secondary science: Research into children’s ideas. London and New York: Routledge Falmer. Keeley, P. 2005. Science curriculum topic study: Bridging the gap between standards and practice. Thousand Oaks, CA: Corwin Press. Keeley, P., F. Eberle, and C. Dorsey. 2008. Uncovering student ideas in science: Another 25 formative assessment probes, volume 3. Arlington, VA: NSTA Press. Keeley, P., F. Eberle, and L. Farrin. 2005. Uncovering student ideas in science: 25 formative assessment probes, volume 1. Arlington, VA: NSTA Press. Keeley, P., F. Eberle, and J. Tugel. 2007. Uncovering student ideas in science: 25 more formative assessment probes, volume 2. Arlington, VA: NSTA Press. Konicek-Moran, R. 2008. Everyday science mysteries. Arlington, VA: NSTA Press. Konicek-Moran, R. 2009. More everyday science mysteries. Arlington, VA: NSTA Press.

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REFERENCES AIMS Education Foundation. 2006. By golly, by gum. Jaw Breakers and Heart Thumpers. Fresno, CA: AIMS. American Association for the Advancement of Science (AAAS).1993. Benchmarks for science literacy. New York: Oxford University Press. National Research Council (NRC). 1996. National science education standards. Washington, DC: National Academies Press.

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Chapter 17

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Chapter 18

About Me

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V

icki loved spending her summers with her aunt Maureen and Uncle Ben. It wasn’t so much that her mother’s sister and her happy-go-lucky husband were so good to her, although they were. But it was sharing room with her cousin Nan that made the time so extra special. Nan was a very sophisticated 14, two years older than she was, and had wonderful smelling shampoos and conditioners, exciting smooth-feeling creams designed not only for their faces, but for their arms and legs as well. Nan sometimes wore lipstick and mascara, things Vicki was not allowed to have although she longed for them. At Nan’s she was not “too young for these things,” and Nan let her use the cosmetics, “sparingly,” as Nan said. That meant, until Nan said “enough!” One rainy day, while there was little else to do, the girls were trying some new makeup in front of the mirror. Vicki noticed that her ears were very different from her cousin’s. “Hey!” she blurted, “your ears were especially made for earrings.” “What are you talking about?” said Nan. “Well,” explained Vicki, “your earlobes hang down. Look at mine, they’re attached right to my jaw.” Nan looked carefully from her own face to her cousin’s. “So, is there a point to this?” she asked impatiently. “Why is that?” asked Vicki. “I probably got my ears from my mother” ventured Nan knowingly. “I’ve got my mom’s ears and I have my dad’s eyes. I wish it was the other way around, but I think girls get most of their looks from their mothers and guys from their dads” “Huh,” snorted Vicki. “I wish I had Demi Moore’s hair but mine looks more like my dog’s. Anyway, maybe you got your long-lobed ears because your mom wore heavy earrings. Then she passed that on to you.” “Can you roll your tongue?” asked Nan, demonstrating her U-shaped tongue stuck out of her pursed lips. Trying very hard, Vicki’s reflection showed merely a tongue, flat as a board, point out at her from the mirror. “Maybe if I practiced it a while, I could,” said Vicki. “My mom can but my dad can’t,” offered Nan. “But, I don’t know why. Maybe Dad needs to practice it, too.” Vicki looked at her cousin thoughtfully. “How many ways are we alike and different? And I wonder about our parents. Our moms are sisters—are they alike? We ought to do a family tree.” “Yeah,” laughed Nan, “we can run around looking our family over like detectives and copying down drawings of their ears. They would think we were weird.” “Not if we were real careful about it and didn’t tell them,” said Vicki. “That might be a little hard when we come to the tongue rolling part,” Nan chuckled. “Aw what’s the difference, we can tell them we are doing some family research. Maybe we can include Gramps and Grammy.”

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Purpose What child hasn’t heard a comment about having some relative’s eyes or nose or

chin, or even disposition for that matter? Sometimes such characteristics as musical ability or athletic prowess or even sense of humor are added to the list. Just what kinds of characteristics do living things receive from their parents and what kinds of traits do they not? What makes the offspring of any animal or plant have the basic characteristics of the parents? There happen to be a great number of human traits that are inherited from parents that are very visible to the naked eye. In fact, eye shape, ear shape and in particular, ear lobe presence or not, hair color, hair texture (including curly or straight), the widow’s peak, and the ability to roll one’s tongue are very easy to observe and record. The purpose of this chapter’s story is to prompt children to explore traits inherited from parents and grandparents and to realize that they are passed from parents to their offspring.

Related Concepts • Heredity • Genetics

• Inherited characteristics • Variation

Don’t Be Surprised The fact that characteristics are passed on from parents to offspring is true in plants

and in animals other than humans as well, but for young children the realization that beetles only beget beetles and roses only beget roses may be a concept new to them. Another revelation may be that no two individuals are identical. The story also brings up some major misconceptions about heredity, mostly about a characteristic like the ability to roll one’s tongue, that cannot be developed by practice but is inherited. Students sometimes have a rather Lamarckian idea about inheritance. Jean Baptiste de Lamarck (1744–1829) theorized that structural changes in living things could be passed on to future generations, which was a popular theory until Charles Darwin proposed the theory of Natural Selection in 1859 and raised doubts among scientists thereafter. Vicki demonstrates this idea when she says that her cousin’s ear lobes possibly came from the fact that her mother wore heavy earrings. Another idea in the story points out an idea prevalent among children that girls get their traits from their mothers and boys from their fathers. These assumptions should come out when the story is discussed if you help your students see that the various opinions expressed by the characters do not hold water when compared with the reality of a family tree. Another common example is that loss of a limb or change in the body structure of a parent does not transfer to any offspring.

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Chapter 18

Content Background

Sexual reproduction is the evolutionary mechanism that is most credited for the variations among offspring. Without sexual reproduction each of the offspring would be a literal clone of the parent. This, of course, happens among one-celled organisms such as the amoeba, bacteria, and some simple algae. But when each parent contributes half of the genetic material that engineers the development of the offspring, the possible combinations of the many genes is basically infinite. Prior to fertilization, sexual cells are formed in the male and female which contain half the number of chromosomes (which contain the genes that carry the instructions for developing the tissues and organs in the yet-to-be-formed embryo). When the new cell containing genetic material from each parent is formed, it contains the requisite number of chromosomes and genes, half from the male and half from the female. The chromosomes and genes of this cell are reproduced over and over again as the embryo develops so that every cell in the new organism contains the same chromosomes and genes as did the original cell. These genes direct the formation of organs, tissues, and all of the traits exhibited by the new offspring. How is it then, you may ask, that the liver does not have blue eyes or the big toe, blond hair? By a complex mechanism during the embryological development of the new being, certain genes are turned off and others are turned on, affecting the development of the proper tissues in the proper places. For example, when the liver is being formed, those genes that carry instructions for the development of the liver are turned on and all others are turned off. At the same time, other genes, responsible for building other parts of the body are on at the proper time and those not involved are turned off. Thus, unless errors occur in the developmental process, the new offspring has all of the right parts in the right places as determined by the combined genetic code received from the male and the female parents. It turns out that for each set of traits, there are two genes that affect each of the same traits. Some genes are “dominant” over others (the recessive genes) which means that when there are two genes for a certain characteristic and they are different, one gene usually determines the characteristic while the other does not. In flowers, some genes for color are dominant and others are recessive. If however, the two recessive genes are present, the recessive color is expressed in the new offspring. When the reproductive cells of the new organism are being formed, the mix of genes on the chromosomes may distribute themselves in a variety of ways and the next generation may be different in certain traits than the parents. The understanding of genetics is complex and better left for later years, but the key idea here is that each parent contributes half of the new organism’s genetic code and this accounts for the fact that Vicki may have her father’s eyes, while she may have her mother’s chin.

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Related Ideas From the National Science Education StAndards (NRC 1996) K–4: Life Cycles of Organisms

• Plants and animals closely resemble their parents. • Many characteristics of an organism are inherited from the parents of the organism, but other characteristics result from an individual’s interactions with the environment. Inherited characteristics include the color of flowers and the number of limbs of an animal.

5–8: Reproduction and Heredity

• In many species, including humans, females produce eggs and males produce sperm. Plants also produce sexually—the egg and sperm are produced in the flowers of flowering plants. An egg and sperm unite to begin development of a new individual. That new individual receives genetic information from its mother (via the egg) and its father (via the sperm). Sexually produced offspring are never identical to either of their parents. • Every organism requires a set of instructions for specifying its traits. Heredity is the passing of these instructions from one generation to another. • Heredity information is contained in genes, located in the chromosomes of each cell. Each gene carries a single unit of information.

Related Ideas From Benchmarks for science Literacy (AAAS 1993) K–2: Heredity

• There is variation among individuals of one kind within a population.

3–5: Heredity

• For offspring to resemble their parents, there must be a reliable way to transfer information from one generation to the next.

6–8: Heredity

• In some kinds of organisms, all the genes come from a single parent, whereas in organisms that have sexes, typically half of the genes come from each parent.

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Chapter 18

Using the Story With Grades K–4

I am aware that this story may have more interest for girls than for boys. Modification of the story’s beginning and changing the gender of at least one of the characters might be helpful. For example, the story might begin with two cousins spending some time drawing each other in an art activity. The conversation about comparing ear lobes could then continue as written with modest modification of the characters. This would maintain the integrity of the story and its purpose. It is also a distinct possibility that class members may come from families where tracing family traits are impossible. A fictional family tree may be substituted for the children to use. With young children, the standards suggest that we concentrate on their realization of the variation that occurs among members of the same species. All the children will be familiar with the variation in pets and some may even have had the experience of observing a litter of kittens, puppies, or guinea pigs. Children who live in rural situations will be very aware of differences in farm animals when compared to their parents. If they are very young, they may have new brothers or sisters, or cousins who are close to their age and have traits that can be observed and recorded in their science notebooks. Young children may need a graphic organizer provided for their observed records, which can help them to record the traits of their choice that distinguish one relative from another. You may start out by asking them how they tell their siblings or cousins apart. Accept all answers because they have certainly developed ways and means of identifying differences among their relatives. Listing all of these categories, such as eye color, height, hair color, voice, an so on, on a large chart can lead to a discussion about how many ways people or pets differ. Their research into their families or pet families will validate the principle of variation and provide data that will build the first step toward understanding the overall principles of heredity as it is studied as they grow and mature.

Using the Story With Grades 5–8 Once again, girls will identify with this story line but boys may have difficulty relat-

ing to the characters. I suggest modification if you feel this will be a problem. The discussion that follows the reading of the story will probably not differ much from that held by younger children except for the sophistication of the responses. I would be surprised if the terms genes, DNA, or even chromosomes did not enter the discussion. The popular media have certainly put these terms before the public, and everything from drug commercials about choleresterol to crime dramas will have at least made the terms familiar. Recognition and usage of the terms should not be construed with understanding; as you know, children and adults alike often use terms without understanding. We must pay attention to the research that tells us that middle and even high school students exhibit misconceptions about how traits are inherited. You may want to consider using the Probe, “Baby Mice,” in Uncovering Student Ideas in

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Science, Volume 2: 25 Formative Assessment Probes (Keeley, Eberle, and Tugel 2007) to find out what your students already think about the topic of heredity. Most of the misconceptions related in the story may be held by your students and the development of a family tree will help point out how these misconceptions do not hold water. All it will take is a few boys who inherit traits from their mothers (or girls from their fathers) to cast doubts on the idea that boys and girls inherit traits only from their same sex parents. Your discussions may also lead you into the areas of inherited diseases like diabetes and sickle cell anemia. They may also realize that there are some sex-linked traits such as pattern baldness and colorblindness that occur. This can lead into the link between reproduction and inheritance, which is not fully understood by a large section of our population. Children in middle school may be ready for the concept of probability and randomness in the distribution of genes in sexual reproduction. If it is possible, I highly recommend the use of the Wisconsin Fast Plants in the classroom. These modified tiny Brassica plants (relatives of broccoli, cauliflower, and cabbage) have been genetically designed to go through an entire life cycle from seed to flower to seed in weeks. Students can pollinate the flowers and gather data on several generations of plant characteristics through use of these marvelous classroom aids. They take up relatively little space and require only a growing table with fluorescent lighting and of course, care and watering by the students. These plants allow you and your students to observe what was never before available, several life cycles of plants in a relatively short space of time. There are a great many ideas for teaching upper elementary and middle school students about heredity but the main purpose of the story is to allow students to confront their preconceptions about this concept and engage in activities that involve their inquiry into the topic. Developing family trees and connecting information about genes and reproduction will provide opportunities for deeper understanding of terms they have been seeing and using superficially. You might be interested in participating in a genetic database that is run from the internet. In this program, students from all over the world contribute and tabulate data on dominant and recessive traits and thereby are participating in a much larger gene pool with global results. The website is: http://k12science.org/ curriculum/genproj/ . It usually starts in the fall of the year.

Related Books and Journal Articles Bryant, R. 2003. Toothpick chromosomes. Science Scope 26 (7): 10–15.

Cowden, N. 2002. The Alien Lab: A study in genetics. Science Scope 26 (2): 24–27. Driver, R., A. Squires, P. Rushworth, and V. Wood-Robinson. 1994. Making sense of secondary science: Research into children’s ideas. London and New York: Routledge Falmer.

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Chapter 18

Hazen, R., and J. Trefil. 1992. The code of life. In Science matters: Achieving scientific literacy, 224–242. New York: Anchor Books. Keeley, P. 2005. Science curriculum topic study: Bridging the gap between standards and practice. Thousand Oaks, CA: Corwin Press. Mesmer, K. 2006. Making Mendel’s model manageable. Science Scope 29 (6): 24–27. Rice, E., M. Krasny, and M. Smith. 2006. Garden genetics: Teaching with edible plants. Arlington, VA: NSTA Press. Stanford, P., and S. Heinhorst. 1997. A blueprint for our bodies. Science and Children 34 (4): 12–15.

References American Association for the Advancement of Science (AAAS). 1993. Benchmarks for science literacy. New York: Oxford University Press. Keeley, P., F. Eberle, and J. Tugel. 2007. Uncovering student ideas in science: 25 more formative assessment probes, volume 2. Arlington, VA: NSTA Press. National Research Council (NRC). 1996. National science education standards. Washington, DC: National Academies Press.

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Chapter 19

A Tasteful Story

T

yrone and Zach were spending a boring afternoon on Zach’s porch. It was too hot out to do anything strenuous and since school was out for the summer they had a lot of time to do nothing. The public swimming pool was closed for the

day for cleaning so they played cards for a while, and in desperation, picked up some of the magazines and newspapers that were lying around. “Hey, Ty, look at this article about your tongue.” “What about my tongue?” said Ty.

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“Not your tongue!” laughed Zach. “It’s about everybody’s tongue.” “You know, Zach, I know it’s kinda boring this afternoon but I can’t figure out why you are getting excited about an article on somebody’s tongue.” “No, it’s about everybody’s tongue. The article in this paper Dad got at the supermarket says that we only taste certain tastes on special locations on our tongues.” “So?” said Ty impatiently. “Well, it says that we can taste sweet on the tip of our tongues and behind the tip on both sides we can only taste salt, and behind that sour, and in the very back where you feel like gagging, you taste bitter things.” “So?” repeated Ty. “Makes sense to me if it’s in the papers.” “You believe everything you read in papers like this one from the supermarket?” “Well, maybe and maybe not. It depends on the paper and whether or not it makes sense.” “You know Ty, I think we ought to try this out and see if it’s really true. Something doesn’t seem right here because I think I can taste salt wherever it is on my tongue.” “That’s easy enough to do,” said Ty. “Let’s go in the kitchen and find some stuff and put it on your tongue.” “Why my tongue?” said Zach. “You want to know too!” “It’s your article, so you ought to get first crack at it. Anyway, let’s look it up in some books or the internet and maybe they’ll tell us the truth about all of this.” So they did, and you know what? Ty and Zach got all kinds of answers and still didn’t know what to believe. “Well,” said Zach, “I guess there’s only one thing we can do and since we don’t seem to have anything else exciting to do, I guess we ought to find out for ourselves. And I’ll volunteer to go first if you will do it too. But I want to check stuff out with Mom first so we don’t get into anything poison by accident.” “Okay” said Ty. “Let’s see if we can get her to give us some stuff that’s bitter or salty or sour or sweet that we can use.”

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Purpose Hardly a day goes by without something arriving by e-mail or being posted on

the internet that just doesn’t sound true. How many e-mail virus warnings have you received in the last few months? At the supermarket, we are all bombarded by news that is little more than paparazzi hype about the current celebrities or rumor, at best (not to mention stories such as those about women giving birth to twoheaded alligators!). The boys in this story are depicted as having alert skepticism about things that don’t actually add up in their minds and determining to find out for themselves. Actually, the tongue map has been around for a long time, even in textbooks. Just recently, it has undergone scrutiny and was found to be a myth. At least, so say some “experts.” Therefore, the purpose of the story is threefold: (1) to design the proper test for the tongue map; (2) to encourage the alert skepticism we want our students to display when confronted with seemingly discrepant information; and (3) to learn something about the nervous system and how it works.

Related Concepts • Senses • • • •

Experimental design Functions of living things The nervous system Urban legends

• • • •

Propaganda Experience Cells and organs Brain function

Don’t Be Surprised There hasn’t been a great deal of research on children’s thinking about taste and,

with the exception of vision, only a small amount about the other senses. However, don’t be surprised if your students are unaware of the function of nerve endings on their bodies and how these send impulses to the brain where they are deciphered. In fact, many students do not understand the dominating role of the brain in everything we do, waking or sleeping. This will be especially important when you discuss with them the various taste responses—sweet, salty, bitter, and sour and possibly a new one called umami—which are names given to responses in our brains to certain chemicals. Umami, a Japanese word for “savory,” is a response to glutamates found in monosodium glutamate (MSG). We should probably leave this one alone since some people are allergic to it. Also, don’t be surprised that your students might be susceptible to “urban legends” and regale you and the class with many untrue statements that have made the rounds over the years. Many of these can be debunked by quick checks in scientific references. Examples include: Gum takes seven years to digest if you swallow it; a cat always lands on its feet; warm water freezes faster than cold; lightning doesn’t strike twice in the same place; a dog’s mouth is cleaner than a human’s, or

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Chapter 19

the yearly e-mail announcement that Mars will be as big as the Moon in the sky. There is a difference between cynicism and skepticism, and the latter will serve the student better in the long run.

Content Background The human nervous system has specialized cells throughout the body that are

connected in such a way that they communicate with once another. These cells are called neurons. In the tongue map, we are talking about cells that are called receptors. These respond to heat, pain, pressure, or, in this instance, taste. The two main nervous systems are the central (including the brain and the spinal cord) and the peripheral, which is spread all over the body and connects to the spinal cord through a set of 31 different pathways. There are three kinds of neurons in the peripheral system: the motor, the sensory, and the autonomic neurons. The autonomic neurons control your heart, lungs, digestive system, and the other parts of your body that work without your conscious attention. We are talking about sensory neurons in this story, because they are the cells that transmit information to the central nervous system about changes within the body or outside the body. Information is sent via an electrochemical wave we call an impulse. The impulse travels through a part of the neuron called an axon to the cell’s end, where it jumps the space between neurons called a synapse. It travels across the synapse using chemical messengers called neurotransmitters. The impulse thus moves on from one neuron to another until it reaches the central nervous system and the brain, where it is decoded and identified. Sometimes certain messages are decoded by the spinal cord and the reaction is quick and unconscious. This is called a reflex action and happens when you touch something sharp or painful. For example, when you touch a hot stove, you withdraw your hand immediately and without thought. If you had to think about it, you might suffer damage to your body, so the body doesn’t wait for you to make a decision. The tongue is covered with tiny nerve endings called papillae, and in some of these papillae are the taste buds that transmit the nature of the chemical that has been in contact with the tongue or oral cavity. Once the message has reached the brain, it is decoded as one of the five different tastes. At the same time, your nose is also at work through its sensory cells, and these combine with the taste transmissions to give us what we call flavor. Without flavor, our sense of taste is diminished and we have a difficult time telling what we are eating. You may have experienced this when you had a head cold and couldn’t smell. Food doesn’t taste the same. Once I was given an antibiotic that masked both my sense of smell and taste. It was very frustrating. After the antibiotic had run its course for about a month, I remember my relief as I finally was able to smell my wife’s special pasta sauce cooking in the kitchen and realized that I was going to

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have a meal that night that I could actually taste. We take these pleasant sensations for granted until we lose them. We have learned over time to distinguish among the many kinds of stimuli that enter our mouths. We know that most medicines and black coffee are bitter. We know that candy is sweet and, of course, salt is salty, as are certain sauces which have been fermented, such as soy sauce. Sour can be either delightful or repulsive, depending on the strength of the acid that produces it. My grandmother used to make pickles that we called “icicle pickles” because they were so sour we shivered when eating them. Over time, I developed a craving for these extra sour pickles and found that certain brands of pickles were more sour than others. In the early 20th century, a German scientist wrote a paper in which he mapped out certain areas of the tongue that he believed were more sensitive to certain tastes than others. In the translation of the article, the belief was probably overstated, but it caught on with the press. Even textbook authors picked Erroneous Tongue Map it up and continued the misinformation—even to this day. This is a great lesson to all of us to be alert to written material that does not make real sense. Just because something is in print does not make it true. The best way to check it out is to try your own investigation. This experiment lends itself easily to the classroom, where the teacher can provide safe-to-use materials for the students to test on one another’s tongues. The erroneous tongue map is only one of many examples of how science information is constantly changing. For example, when I was in school studying biology, all texts said that there were 24 pairs of human chromosomes. Someone did a recount later (in Florida perhaps) and discovered that there were only 23 pairs. As science progresses, changes are made to theories in order to fit new information or to solve age-old problems. For example, the change in biological taxonomy from two kingdoms to five kingdoms occurred recently, mainly because the new classification helped to place organisms in more appropriate groups. The outdated tongue map demonstrates insufficient testing of a theory before making it into a universal fact. The latest research seems to tell us that all of the taste buds are capable of detecting all of the tastes, even though some areas are slightly more sensitive to certain tastes than others. Most of these differences, however, are hardly measurable. I believe that if you put salt on the tip of your tongue, you will be aware of salt regardless of the “map” that says the tip of the tongue only senses sweetness.

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Chapter 19

Bitter Sour Salty Sweet

Related Ideas From the National Science Education Standards (NRC 1996) K–4: The Characteristics of Organisms

• The behavior of individual organisms is influenced by internal cues (such as hunger) and by external cues (such as a change in the environment). Humans and other organisms have senses that help them detect internal and external cues.

K–4: Understanding About Scientific Inquiry

• Scientific investigations involve asking and answering a question and comparing the answer with what scientists already know about the world. • Scientists use different kinds of investigations depending on the questions they are trying to answer. Types of investigations include describing objects, events, and organisms; classifying them; and doing a fair test (experimenting). • Scientists develop explanations using observations (evidence) and what they already know about the world (scientific knowledge). Good explanations are based on evidence from investigations.

5–8: Structure and Function in Living Systems

• The human organism has systems for digestion, respiration, reproduction, circulation, excretion, movement, control and coordination, and for protection from disease. These systems interact with one another.

5–8: Regulation and Behavior

• Regulation of an organism’s internal environment involves sensing the internal environment and changing physiological activities to keep conditions within the range required to survive. • Behavior is one kind of response an organism can make to an internal or environmental stimulus. A behavioral response requires coordination and communication at many levels, including cells, organ systems, and whole organisms. • Scientists make the results of their investigations public; they describe the investigations in ways that enable others to repeat the investigations. • Scientists review and ask questions about the results of other scientists’ work.

5–8: Abilities Necessary to Do Scientific Inquiry

• Identify questions that can be answered through scientific investigations. Students should be able to identify their questions with scientific ideas, concepts, and quantitative relationships that guide investigations.

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• Design and conduct a scientific investigation. Students can learn to formulate questions, design investigations, execute investigations, interpret data, use evidence to generate explanations, propose alternative explanations, and critique explanations and procedures. • Think critically and logically to make the relations between evidence and explanations. • Recognize and analyze alternative explanations and predictions. • Understandings about scientific inquiry. Science advances through legitimate skepticism. Scientists evaluate the explanations proposed by other scientists by examining evidence. Comparing evidence, identifying faulty reasoning, pointing out statements that go beyond the evidence and suggesting alternative explanations for the same observations.

Related Ideas From Benchmarks for Science Literacy (AAAS 1993) K–2: The Human Organism: Basic Functions

• The human body has parts that help it seek, find, and take in food when it feels hunger—eyes and noses for detecting food, legs to get to it, arms to carry it away, and a mouth to eat it. • Senses can warn individuals about danger; muscles help them to fight, hide, or get out of danger. • The brain enables human beings to think and sends messages to other body parts to help them work properly.

K–2: The Scientific Enterprise

• Everybody can do science and invent things and ideas. • In doing science, it is often helpful to work with a team and to share findings with others.

3–5: The Human Organism: Basic Functions

• The brain gets signals from all parts of the body telling what is going on there. The brain also sends signals to parts of the body to influence what they do.

3–5: The Scientific Enterprise

• Clear communication is an essential part of doing science. It enables scientists to inform others about their work, expose their ideas to criticism by other scientists, and stay informed about scientific discoveries around the world.

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Chapter 19

6–8: The Scientific Enterprise

• No matter who does science and mathematics or invents things, or when or where they do it, the knowledge and technology that result can eventually become available to everyone in the world.

Using the Story With Grades K–4 After reading the story, the children will want to find out if the tongue map applies

to them or not. Young children may need help understanding the function of a map. You can draw a picture of the map shown above and ask them if they believe it or not and ask how they might go about finding out for themselves. This is a good time to talk with them about variables and designing a fair test. One way to do this is to try a simple experiment with them and make some obvious unfair choices in your execution. For example, set up a ramp and place two different balls at the top of the ramp and ask which will reach the bottom first. After they have predicted, place one ball halfway down the ramp or push one ball and just release the other. The cries of “not fair” will give you an opportunity to elicit from them what variables need to be controlled to have a “fair” test. I would like to mention a word about safety here. In most classrooms, teachers forbid children to put anything into their mouths. In this activity, you have to deviate from this rule. Assure them that the materials you have provided are completely safe and remind them that this is an exception to the rule and that they should never put things into their mouths unless they are given explicit instructions by you. You’ll notice that in the story Zach says that he wants his mother to check the materials to make sure they are safe. I suggest that you use either flat toothpicks or preferably cotton swabs for transferring the liquids to the tongue. Liquids are best to use, since in small amounts they cannot be inhaled by accident and the dissolved form gives better results. Lemon juice is great for sour, instant coffee is good for bitter, honey in water for sweet and, of course, salt water for salty. You also can try to elicit from the children what they would like to try. They may have some unique ideas that would make the activity even more personal for them. It is usually best to have the children divide into pairs and have each member of the pair test the other by placing a small amount (stress this) of the liquid via the cotton swab on the various sections of the tongue and see if the subject can identify the taste. The applicator should make sure all parts of the tongue map are tested. You and the students should probably devise a common data sheet for display after the activity. The sheet should include the order in which the substances were applied and the reaction of the subject to each substance. A typical response would be, “Johnny tasted salty on all parts of his tongue” or “Mary only tasted bitter in the back of her tongue.” At this level it is unlikely that the students will consider that the order of tastes attempted is important, but with older age children, this might come up. Children may also like to wash out their mouths with water between tests. It might be

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good to provide a small container to each pair so they can spit out their rinse water, although my experience is that children don’t usually need to do this. Experience tells us that the bogus map will be disproved but some students will say that they agree with the map. You can respond that everyone is different in some little detail and that the main problem with the bogus map is that it was purported to be universal. This lesson allows students to design and conduct an investigation with a fairly large population (the entire class). They will also have seen that all that is in print is not necessarily true.

Using the Story With Grades 5–8 The following is an account written by a teacher, Susan Johnson, who worked

with the tongue map and found that it was successful in getting children involved. I quote directly so that you can see how she handled the concepts involved and how she evaluated her own teaching as well as the students’ work. Although Susan is a biology teacher, I believe that middle school students can relate to her lesson quite easily. Traditionally, during the anatomy and physiology unit, I briefly mention the “tongue map,” and show the students a diagram of this map, which divides the tongue based on salty, sweet, bitter, and sour. However, I did not allow the students the opportunity to test the tongue map; I only explained that it was developed and then recently disproved. To make the tongue map more meaningful, I decided to modify this lesson so the students would develop the tongue map themselves. I first asked the class to develop a list of the different types of things they can taste, and they were able to come up with the four: salty, sweet, bitter, and sour. Then we brainstormed a list of foods that fit into each category. Next, the class voted on which items from their list would be best to use when developing a tongue map. They decided on the following: sweet = sugar cubes, salty = saltwater, bitter = coffee, and sour = Sour Patch Kids candy or lemon juice. The testing material for sour became a topic for debate. Some students argued that Sour Patch Kids are sour enough that they will be sufficient for tongue mapping; however, another student pointed out that once the sour coating is gone, sour patch kids taste sweet and the sour flavor is mixed with sugar, which is sweet. They decided that lemon juice would be better for sour, since it does not have a sweet taste. Another student noticed that three of the four taste testing items were liquid, and recommended that we use sugar water instead of sugar cubes, so that we could “swish” it around in our mouths. The class voted and decided that sugar water would be used in place of sugar cubes.

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Chapter 19

The class was then asked to develop a technique for taste testing. Students decided that they needed to rinse their mouths with fresh water between taste tests. Another student asked if the order that the different tastes are tried might affect the result. We then had to generate the number of possible taste testing orders. The students discovered 24 combinations and they wanted to try all 24. There were only 23 students in the class, so they decided that I needed to participate. Each person would get one of the combinations and would rinse with water in between each trial. The next day I brought in lemon juice, saltwater, sugar water, and coffee. Each of us carried out our trial, and then constructed an individual tongue map on a piece of blank paper, which we then posted on the wall. The class then analyzed the various tongue maps and divided them into categories based on their similarities. Once we had grouped them, I showed them the accepted tongue map. Students who did not match the tongue map were distraught and insisted they were correct. Some students were certain they could taste all four flavors everywhere on their tongue! More investigation was needed. One student suggested we try putting each of the four flavors on each of the regions on our tongues. So we did... and all the students found that they could taste all four flavors on every region of their tongues! What happened to our tongue map? Although students said that they could taste different flavors more in certain spots, they did say that they could taste all flavors over their entire tongue. Finally, I let them in on the tongue map “myth” and we read an article (“The Tongue Map: Tasteless Myth Debunked” www.livescience.com/health/060829_ bad_tongue.html). This activity went well, and all of the students were really engaged. Even the students who have been very apathetic throughout the year were animated and had strong opinions when it came to arguing for their particular tongue map. Although this activity took two days to complete, I feel like it was useful. Students were able to ask questions and explore the answers to those questions. And there you have it. I could not have described the activity any better than that! Just as in any classroom, it may well be necessary to develop a common data chart so that the results can be compared. Some teachers try to wean their students from standardized data sheets.

Related Books and Journal Articles Driver, R., A. Squires, P. Rushworth, and V. Wood-Robinson. 1994. Making

sense of secondary science: Research into children’s ideas. London and New York: Routledge-Falmer. Keeley, P. 2005. Science curriculum topic study: Bridging the gap between standards and practice. Thousand Oaks, CA: Corwin Press.

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Keeley, P., F. Eberle, and C. Dorsey. 2008. Uncovering student ideas in science: Another 25 formative assessment probes, volume 3. Arlington, VA: NSTA Press. Keeley, P., F. Eberle, and L. Farrin. 2005. Uncovering student ideas in science: 25 formative assessment probes, volume 1. Arlington, VA: NSTA Press. Keeley, P., F. Eberle, and J. Tugel. 2007. Uncovering student ideas in science: 25 more formative assessment probes, volume 2. Arlington, VA: NSTA Press. Parlier, D., and M. K. Demetrikopoulos. 2004. A touch of neuroscience. Science Scope 28 (2): 48–50.

References American Association for the Advancement of Science (AAAS). 1993. Benchmarks for science literacy. New York: Oxford University Press. Johnson, S. Final paper for Educ. 610, University of Massachusetts. Used with the permission of the author. National Research Council (NRC). 1996. National science education standards. Washington, DC: National Academies Press. Wanjek, C. 2006. The tongue map: Tasteless myth debunked. www.livescience. com/health/060829_bad_tongue.html.

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Chapter 20

Reaction Time

F

ouad and his brother Abdul were playing a game of “hand slap,” which they had learned in their native land. In this game, sitting opposite one another on the floor, one player places his hands face up on his lap and the other lays his hands face down on top of the first player’s hands, palm to palm. The one whose hands are on the bottom tries to take his hands away fast and slap the hands of the

other before they are pulled back. This requires a great deal of quickness to feel the other’s hands move and pull back so that your hands cannot be slapped. And it takes speed to remove your hands quickly without being noticed and to slap the hands of the other person. People often call this reaction time. Fouad seemed to win at this game more than his brother and liked to brag a little about it.

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“I have such a good jump on you, Abdul! I know when you are going to move your hands before you do yourself. I have excellent reaction time.” “Well, maybe you do win more than I do but I think I have really good reaction time too.” “Well, you sure don’t show it in the game,” said Fouad. “If you can’t win at hand slap, why do you think you have good reaction time?” “Because I am quick at other games. You only beat me at this one!” “I saw something in a magazine that will help us to decide who is faster!” said Fouad. “Do you want to give it a try?” “Sure, as long as it’s fair,” said Abdul. “What is the test?” “You have to get a meterstick first. One person holds it at the top and the other person opens his first finger and thumb apart at the bottom of the stick. The person who is holding the stick lets it go and the other person pinches his fingers together as soon as he notices the stick falling to try to stop it. How far down the stick travels measures how fast the other person reacted. The less the stick falls, the quicker you grab it and the better your reaction time.” “That sounds cool! I think I can think of all kinds of reaction times we can measure with that test. Let’s get a meterstick and do it! But remember we have to make sure it’s fair.” “Okay, we’ll make sure it’s fair but what do you mean by different kinds of reaction time?” “You’ll see,” said Abdul. “Maybe you won’t be the best at all of the different kinds.”

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PURPOSE This story provides the opportunity for students to learn about how our nervous system responds to stimuli and to find out how our nervous system works.

RELATED CONCEPTS • Nervous system • Stimuli • Averages

• Simple reaction time • Responses

DON’T BE SURPRISED Students may have the impression that all kinds of reaction time responses can be improved through practice. They may believe also that every kind of stimulus produces the same kind of reaction time. They are not usually aware of the importance of the central nervous system’s role in determining reaction time.

CONTENT BACKGROUND Reaction time is the interval of time between the presentation of a stimulus and

the resulting behavioral reaction in any living organism. In sports, reaction time is crucial. Take for example, baseball: A major-league league pitcher stands about 60 feet and 6 inches from the batter who is armed with a bat. Many pitchers can throw a baseball at 95 miles per hour or faster. That means the ball reaches the batter in approximately 0.4 seconds. The batter has about .04 seconds to decide where or even whether to hit it at all. That requires very fast reaction time. Most batters have trouble doing so, and hit the ball less than 3 times in 10. Any more than that and the batter is considered to be an excellent hitter. In 1941, Ted Williams was one of only seven hitters since 1903 to hit over .400 (four hits out of every 10 times at bat). Wildlife experts tell us that predators like the cheetah and the lion are successful only 3 times in 10. Life is tough in the wild and on the baseball diamond! This story has to do with the reactions of the nervous system. In many animals there are two parts to the nervous system, the central and the peripheral. The central nervous system is made up of the brain, the spinal cord, and the retina. The peripheral nervous system is made up mainly of sensory neurons that are connected to the central nervous system. Comprised of cells called neurons, the nervous system sends signals from neuron to neuron via electrochemical waves that travel along very thin fibers called axons. Chemicals called neurotransmitters are released at the junctions of these cells, called synapses, which allow the signal to continue on to their destinations via the next set of axons.

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Chapter 20

For example, when a person reacts to a visual stimulus, many things have to happen before that reaction takes place. The stimulus (in the form of light particles or waves) enters the eye and then goes, via the neurons or neural pathways to the brain where it is processed and a response chosen. The response or directions for physical reaction is then sent over the myriad of neurons to the spinal cord. The spinal cord sends the impulse on to the proper muscles, telling them how to react. Clearly, then, there are a lot of transfers of this electrical-chemical information, but it is all happening at super speed. But hey, sometimes even that is too slow for your own good! Suppose someone throws something and it comes your way—maybe even at your face. A reflex action takes place in this case and the message goes directly to the spinal cord, bypassing the brain. You duck or blink your eyes to avoid contact. Similarly, you may touch something hot. The receptor in your skin sends the message “HOT!!” to your spinal cord that immediately causes you to pull back. Your brain doesn’t get a chance to “think” about it. Good thing too because it can often save you from serious injury. But now back to the story and reaction time. Reaction time does involve the brain. In certain situations, known as simple reactions, where a person reacts to a single stimulus and responds with a conscious action, a sensory organ or nerve (using sight, hearing, or touch) is involved and the neurons send the message to the brain, then to the spinal cord and on to the muscles. It is “hard wired” and does not usually improve beyond a certain point even with practice. It also hits its peak in the teens and then usually goes downhill progressively with age. I suspect that is why some professional athletes are “over the hill” by age 35. That 95-mileper-hour fastball begins to look like an aspirin tablet and is, more often than not, a strike, either looking or swinging. The internet is loaded with different reaction time tests that you can try. The reaction time tester referred to in the story is a simple one and uses only a meterstick or yardstick found in most households. You and some of your more interested students might like to read a literature review by Robert Kosinski of Clemson University at http://biology.clemson.edu/bpc/bp/Lab/110/reaction.htm. This way your students can see that scientists at major universities are doing research on the same topic as they are. This should end doubts that they too, can be real scientists. There is also a different type of test that is called a “go/no-go” test in which the subject must decide between two stimuli and either react or not react depending upon the directions. For example, the subject may have to refrain from responding to a certain stimulus and respond to another. Therefore, the brain must process more than one symbol and then tell the subject how to respond (or not). This of course takes much more reaction time and is not mentioned in the story because it is much too complicated to measure in a classroom with everyday materials. However, the test is available online at http://cognitivefun.net/test/17.

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RELATED IDEAS FROM THE NATIONAL SCIENCE EDUCATION STANDARDS (NRC 1996) K–4: The Characteristics of Organisms

• The behavior of individual organisms is influenced by internal cues (such as hunger) and by external cues (such as a change in the environment). Humans and other organisms have senses that help them detect internal and external cues.

5–8: Regulation and Behavior

• Regulation of an organism’s internal environment involves sensing the internal environment and changing physiological activities to keep conditions within the range required to survive. • Behavior is one kind of response an organism can make to an internal or environmental stimulus. A behavioral response requires coordination and communication at many levels, including cells, organ systems, and whole organisms. A behavioral response is a set of actions determined in part by heredity and in part from experience.

5–8: Structure and Function in Living Systems

• Specialized cells perform specialized functions in multicellular organisms. Groups of specialized cells cooperate to form a tissue, such as a muscle. Different tissues are in turn grouped together to form larger functional units, called organs. Each type of cell, tissue, and organ has a distinct structure and set of functions that serve the organism as a whole. • The human organism has systems for digestion, respiration, reproduction, circulation, excretion, movement, control, and coordination, and for protection from disease. These systems interact with one another.

RELATED IDEAS FROM BENCHMARKS FOR SCIENCE LITERACY (AAAS 1993) K–2: Basic Functions

• Senses can warn individuals about danger; muscles help them to fight, hide, or get out of danger. • The brain enables human beings to think and sends messages to other body parts to help them work properly.

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Chapter 20

3–5: Basic Functions

• The brain gets signals from all parts of the body telling what is going on there. The brain also sends signals to parts of the body to influence what they do.

6–8: Basic Functions

• Organs and organ systems are composed of cells and help to provide all cells with basic needs. • Interactions among the senses, nerves, and brain make possible the learning that enables human beings to cope with changes in their environment.

USING THE STORY WITH GRADES K–4 What do you think your kids are going to want to do first? The hand slap game,

right? It is described pretty thoroughly in the story. The children can see that stealth and quickness win this game. Ask them to analyze the game and try to decide what they are each doing to fool the other person. They should be able to see that it is how quickly the person with hands on top can sense the movement of the other person’s hands that make it possible to avoid the slap. Players usually set a number such as 10 tries to see who wins the game and then the partners switch roles and try again. Scoring can be at the discretion of the players. Questions usually arise, such as: • Do you get better with practice? • Do you develop a strategy to fool the other person? • Do you think your reaction time gets any faster or do you just figure out your opponent’s moves? (Note: Actual response time is hard wired but strategies do develop with practice.) • Are you able to do better with an older person? A younger person? Being the teacher, you’ll have to accept challenges about the last question and prepare to lose since reaction time does get slower as you age. But, you can accept defeat in the interest of education, right? With children in second grade and above you should feel comfortable in letting them try to measure reaction that will result in numerical data. The only piece of equipment you will need is a ruler, yardstick, or meterstick. Again, this is described pretty thoroughly in the story. The stick should be held so that the bottom is in line with the thumb and finger of the “catcher.” The “dropper” drops the stick without warning and the catchers pinch thumb and finger together as quickly as possible. The distance the stick fell can be measured by seeing where the middle of the thumb or finger is on the stick. This distance can be recorded in the science notebooks and analyzed to see if there are changes as trials progress. Again, the reaction time will not change but catching strategies may make a difference as practice continues. Fatigue, loss of interest, or boredom can have an affect on the reaction time as well as drugs, even coffee. I have already mentioned

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age as a factor. Reaction time shortens from infancy until the 20s and then begins to lengthen slowly until about the 50s and 60s. After that, the response lengthens more quickly with advancing age. At my age (81), I guess that leaves me pretty much close to coming in last place! And, sorry women, but females seem to be a bit slower than males on average (Der and Deary 2006). We have evidence that auditory stimuli result in shorter reaction times than visual stimuli (Brebner and Welford 1980). This seems to be because it takes less time for an auditory stimulus to reach the brain for processing than a visual one. It also seems that in computer mouse tests, left-handed people do better than right-handed subjects (Peters and Ivanoff 1999). This makes sense, as left-handed people often have dominant right brain hemispheres, which is where spatial tasks are performed. There are still many things that are unknown about the neural networks that form reaction time. Students have been known to raise some new and interesting questions. These may be too sophisticated for very young children but if you have a class that seems able to handle more difficult tasks, read the next section and see if your children could do some of them.

USING THE STORY WITH GRADES 5–8 It should not surprise anyone if middle school students wanted to begin working with the hand slap game just as much as the elementary age children. They may wonder what Abdul is talking about when he says that Fouad may not be best at all kinds of reaction time tasks. Once they have tried the meterstick drop, my experience is that the students will come up with many more questions than you will. Each is usually investigable and deserves to be tested. Some will be: • • • • • •

How will an auditory stimulus affect reaction time in a blindfolded subject? How will a touch stimulus affect reaction time in a blindfolded subject? How does age affect reaction time? Does age affect reaction time in all tasks? Does gender affect reaction time? Does handedness affect reaction time?

Fouad and Abdul stressed that the tests be fair and so they should. You can help students make sure that all variables are maintained in a proper way regardless of the question being investigated. Data collected in all tests should be recorded, both in individual notebooks and as a class. It is wise to do this anonymously so that some less-quick students do not feel embarrassed. You can also think about doing a larger test including more than one class or testing across ages. Graphing can be introduced as a way to use a pictorial summary of data. You will probably end up with a bell-shaped curve, with atypical results at the extremes and the more typical results in the middle. This also is a good introduction to statistics. Students can use statistics to predict the most likely results for individuals who are tested after the graph is made.

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Chapter 20

You will undoubtedly have to put an end to the investigations because the students will want to continue to test new ideas and new groups of individuals. But, all in all, I think I can promise you that your class will involve themselves in real inquiry and data collection and that it will be worthwhile for many pedagogical reasons. For individuals who want to be challenged, you can use your internet search engine to find more reaction time tests online that will be both fun and informative. Please take time to do this since you will be able to use various stimuli and tests like “go/no go” time reaction in an entertaining way.

RELATED BOOKS AND NSTA JOURNAL ARTICLES Keeley, P. 2005. Science curriculum topic study: Bridging the gap between standards

and practice. Thousand Oaks, CA: Corwin Press. Keeley, P., F. Eberle, and C. Dorsey. 2008. Uncovering student ideas in science, volume 3: Another 25 formative assessment probes. Arlington, VA: NSTA Press. Keeley, P., F. Eberle, and J. Tugel. 2007. Uncovering student ideas in science, volume 2: 25 more formative assessment probes. Arlington, VA: NSTA Press. Keeley, P., and J. Tugel. 2009. Uncovering student ideas in science, volume 4: 25 new formative assessment probes. Arlington, VA: NSTA Press. Konicek-Moran, R. 2008. Everyday Science Mysteries: Stories for inquiry-based science teaching. Arlington, VA: NSTA Press. Konicek-Moran, R. 2009. More everyday science mysteries: Stories for inquiry-based science teaching. Arlington, VA: NSTA Press. Konicek-Moran, R. 2010. Even More Everyday Science Mysteries: Stories for inquirybased science teaching. Arlington, VA: NSTA Press.

REFERENCES American Association for the Advancement of Science (AAAS).1993. Benchmarks for science literacy. New York: Oxford University Press. Brebner, J. T., and A. T. Welford. 1980. Introduction: An historical background sketch. In Reaction Times, ed. A. T. Welford, 1–23. New York: Academic Press. Cognitive Fun. 2008. http://cognitivefun.net/test/17 Der, G., and I. J. Deary. 2006. Age and sex differences in reaction time in adulthood: Results from the United Kingdom health and lifestyle survey. Psychology and Aging 21 (1): 62–73. Peters, M., and J. Ivanoff. 1999. Performance asymmetries in computer mouse control of right-handers, and left-handers with left- and right-handed mouse experience. Journal of Motor Behavior 31 (1): 86–89. National Research Council (NRC). 1996. National science education standards. Washington, DC: National Academies Press.

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Chapter 21

Worms are for more than bait

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J

im and Hal were walking to school one beautiful day in October. Jim was feeling pretty full of himself and couldn’t stop talking as they walked along. Boy, I really zinged my big sister this morning” he said. “What did you do, put ants in her cereal?” said Hal. “Nah, nothing as obvious as that. No, I was reading this book, Diary of a Worm. It’s about a worm that keeps a diary, and one day he sees his sister looking in the mirror, you know, making faces and turning one way and the other. You must have seen your sister doin’ that. Anyway, in the book, the worm says to his sister something like, ‘No matter how much time you spend looking in the mirror, your face will always look just like your rear end.’” Hal laughed. “For worms, I guess that’s true.” “Yeah, well anyway, I said that to my sister and she freaked out and called Mom and everything. I had to apologize but it was worth it.” “Actually, how do you tell the front end of a worm from the back end?” asked Hal. “I dunno. I never really tried,” said Jim, after thinking a bit. “I guess, now that you bring it up, I’d kinda like to know if you can tell one end from the other. I never looked past putting one on my line when I go fishing.” Hal said, “I know that when my dad and I want bait for fishing, we water the lawn really wet after dark and then the earthworms come to the surface where we can catch them, but we have to use flashlights and walk very softly. They do actually come out headfirst I think, and if you’re not quick enough grabbing them, they go back down the hole like lightning. I really don’t know how they move back down the hole so fast, but on the ground, they can’t move any faster than a slow turtle. But they sure do wiggle a lot. Come to think about it, I don’t know how to tell the males from the females either.” “Let’s ask Mr. Thompson if we can study them,” Jim suggested. “Otherwise we may have to do something boring. Anyway, a lot of kids will be grossed out and that will be cool ’cause we won’t.” They did just that and Mr. Thompson seemed delighted that the boys were interested enough in worms to want to study them. He actually was going to do something with animals anyway, so this was a perfect opportunity to engage the students. The boys already had some good questions about telling one end from the other, about distinguishing males and females, about how earthworms move, and why worms were supposed to be so good for the soil. Mr. Thompson got some live worms and the fun began.

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Purpose Segmented worms are considered “yucky” by a great many people, yet they are

members of a large animal group that populates the entire world and provides a great service to our planet. The story should stimulate students to want to know more about this group of animals—their behavior, life cycles, habits, and their benefit to the Earth. Worms are also cool. Once kids get to know them, they find them very interesting and should become protective of these animals so vital to our ecosystem.

Related Concepts • Life cycles • Animal behavior • Adaptation

• Classification of organisms • Reproduction • Variation

Don’t Be Surprised Worms, because of their legless bodies, their seemingly slimy coverings, and the

fact that they live mostly underground, repel many students. Many people, even adults, have a number of misconceptions about worms. For instance, your students will expect that sexes are separate (i.e., males and females), not hermaphroditic. Students probably also think that you can cut worms into pieces and that all parts will produce new worms (of course, we cannot condone any experiments to investigate this). Your students may think that worms bite, yet worms have no way to do so. They may worry that worms carry disease, but worms do not. Worms are accused of eating dirt and garbage, and to this we plead on their behalf, a hearty and welcome guilty! Actually, it is bacteria that eat the garbage; the earthworms eat what the bacteria leave behind, as well as the bacteria themselves. Children may also believe that all bacteria are harmful. This is not true, since without bacteria decomposition would not take place. In the end, the garbage is turned into compost, a rich and nutrient-packed medium for plant growth. For that, we owe earthworms and bacteria a debt of gratitude.

Content Background Earthworms belong to the phylum Annelida, which means “little rings,” appro-

priately named because their bodies look like they are made up of tiny rings or segments (thus the term segmented worms). There are thousands of kinds of worms in the world, and of these, there are more than 9,000 different kinds of annelids. These may be contrasted with other kinds like the flatworms (phylum Platyhelminthes) and roundworms (phylum Nematoda). Among the three types of worms

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Chapter 21

mentioned above, the majority are nonparasitic (exceptions include some species of roundworms, which are parasitic in humans and other animals, and the tapeworm, a flatworm parasite). Earthworms range in size from half a millimeter (0.02 inches) to more than 7 meters (23 feet)! We are going to focus on the earthworm group, which includes the red worms, earthworms, and night crawlers, mainly because they are the easiest to obtain and the most common. As you may guess, earthworms live in the earth. Earthworms can be small like the red worm or large like the night crawler, which is common fishing bait. Night crawlers travel deeply into the soil, vertically down, sometimes six feet below the surface. Common earthworms tunnel more horizontally just beneath the surface. Red worms are common in vermiculture, the term for the process of turning garbage into compost. Earthworms are also a staple of the diet of predators like the mole and the shrew, which hunt them underground. There have been entire books written on worms, several referenced at the end of the chapter, so I will only mention a few important features of earthworms that will hopefully come in handy when you have your students conduct investigations. Though they are often referred to as “lowly worms,” they are quite complex physiologically. They are tubelike animals with a head and a posterior end (not really a tail). The head consists of a mouth and pharynx leading to an esophagus. At the posterior end is an anus. Inside the earthworm is a crop behind the esophagus where food is stored until it passes into the gizzard, where muscular action, along with some stones, breaks down the food into manageable pieces, after which it passes into the intestine and eventually out of the anus as a casting. In the intestine, circulating red blood (with hemoglobin) carries nutrients from the intestine into the circulatory system to nurture the earthworm’s cells. The earthworm has five hearts that beat rhythmically and circulate the blood throughout the body. It has no eyes but can sense light and vibrations via nerve endings in its body. Each segment has tiny bristles or setae that are used to grasp rocks or other material in the environment so the worm can move. It does this by elongating its body, grasping the surface with its front setae and then shortening its body to catch up to the front end. The rear setae then grasp the stratum while the front end stretches out again and so on. Earthworms do not have lungs and therefore do not breathe, but they do respire and keep their skin moist with mucus so that they can exchange gases from the atmosphere through their skin. Earthworms eat dirt and anything that is in that dirt and will also eat leaves and other botanical food. Thus it is a vegetarian. It is said that they eat garbage to make compost, but it is more correct to say that they eat the bacteria and fungi that decompose the garbage, which then pass through their intestine, where anything useful is extracted. Their tunneling and depositing of mineral-rich castings in the soil serves to enrich and aerate the soil, allowing it to drain better. Charles Darwin is supposed to have said that he doubted that there were any other animals that had played so important a role in the history of the world. Quite an endorsement! Earthworms are hermaphroditic, meaning that they are bisexual. Each worm produces both eggs and sperm, and they mate by lying side by side, heads in the

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opposite direction in order to exchange sperm. On each worm is a saddlelike organ called a clitellum that secretes mucus, which coats the sperm and eggs and then hardens into a cocoon. Tiny worms hatch in the cocoon and emerge as tiny images of the adult. Can you tell the front end of an earthworm from the back? You certainly can. You can infer which end is the front by allowing the worm to move and assume that most of the motion will be in a forward direction. Or you can look for the clitellum, which is located more toward the front than the rear of the body. More clinically, you can use a magnifier to look for the mouth with the overlapping prostomium on the first segment. It looks like a fat little flap of skin or lip that protects the mouth under it. Finally, the tail end is more pointed than the front of the worm.

Related Ideas From the National Science Education Standards (NRC 1996) K–4: The Characteristics of Organisms

• Organisms have basic needs. For example animals need air, water and food; plants require air, water, nutrients, and light. Organisms can survive only in environments in which their need can be met. • The world has many different environments, and distinct environments support the life of different types of organisms. • Each plant or animal has different structures that serve different functions in growth, survival, and reproduction. • The behavior of individual organisms is influenced by external cues (such as a change in the environment). Humans and other organisms have senses that help them detect internal and external cues.

K–4: Life Cycles of Organisms

• Plants and animals have life cycles that include being born, developing into adults, reproducing, and eventually dying. The details of this life cycle are different for different organisms. • Plants and animals closely resemble their parents.

K–4: Organisms and Environments

• All animals depend on plants. Some animals eat plants for food. Other animals eat animals that eat plants. • An organism’s patterns of behavior are related to the nature of that organism’s environment, including the kinds and numbers of other organisms present, the availability of food and resources, and the physical characteristics of the environment.

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Chapter 21

5–8: Structure and Function in Living Systems

• Living systems at all levels of organization demonstrate the complementary nature of structure and function. Important levels of organization for structure and function include cells, organs, tissues, organ systems, whole organisms, and ecosystems.

5–8: Reproduction and Heredity

• Reproduction is a characteristic of all living systems: because no individual organism lives forever, reproduction is essential to the continuation of every species. Some organisms reproduce asexually. Other organisms reproduce sexually.

5–8: Diversity and Adaptations of Organisms

• Millions of species of animals, plants and microorganisms are alive today. Although different species might look dissimilar, the unity among organisms becomes apparent from an analysis of internal structures, the similarity of their chemical processes, and the evidence of common ancestry.

Related Ideas From Benchmarks for Science Literacy (AAAS 1993) K–2: Diversity of Life

• Some animals and plants are alike in the way they look and in the things they do, and others are very different from one another. • Plants and animals have features that help them live in different environments.

3–5: Diversity of Life

• A great variety of kinds of living things can be sorted into groups in many ways using various features to decide which things belong to which group. • Features used for grouping depend on the purpose of the grouping.

6–8: Diversity of Life

• Animals and plants have a great variety of body plans and internal structures that contribute to their being able to make or find food and reproduce. • For sexually reproducing organisms, a species comprises all organisms that can mate with one another to produce fertile offspring.

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Using the Story With Grades K–4 This story has a lot in common with the story called “Oatmeal Bugs” (see Chapter

24). For one thing, worms are about as popular with humans as beetle larvae and secondly, worms are animals that can be kept easily in a classroom or a home without worries about infestation. Worms are interesting to study because they behave in unusual ways, are not visible to the casual observer, but can perform a great service for the ecosystem. First, ask your students to list what they already know about earthworms and place these bits of “knowledge” on chart paper. This is the “Our Best Thinking” chart that will serve as a guide throughout the study. Changing one or two words can then change these statements into questions. These questions then serve as the foci for the investigations carried out by the students. Next is the strategy called “What Can It Tell You and What Do You Want to Know?” It begins with the students observing the worms, drawing, and labeling them in their science notebooks. This is the “What Can It Tell You?” part of the strategy. It focuses on observation and not upon inference. For example, if a worm goes into the dark part of an observation chamber, a student could say, “It went into the darker side of the chamber.” That is an observation. The child could also say, “The worm doesn’t like the light.” That would be an inference. In the first part of the strategy we focus only on observations. Inferences should have some data to back them up. On one occasion when students were a bit sloppy about their observations, I called them to the front of the room and I drew a worm on the board as they gave me directions from their notes. As time went on, we were stymied by the lack of agreement on certain details such as the number of segments, the size of the clitellum, and how many setae per segment. I suggested that they needed to go back to the worm and be more careful about their observations and their notes. We returned the next day and completed the drawing successfully. In the second part of the strategy, “What Do You Want to Know?” the students perform investigations. It should be stressed that at no time should a worm be injured or killed. One of the common misconceptions is that if you cut a worm in half, it will regenerate. Many a worm has met its demise testing this theory. The answer to the question “If you cut an earthworm in half will it make two worms?” is that it depends on what organs you cut. If the first few segments are removed, say by a bird trying to pull a worm out of its burrow, it may grow a new head. But if you cut a worm in half, the posterior end may grow another tail and then starve to death. The literature is sketchy on this whole episode of worm life, so it is best to leave it alone and ask your students to treat their worms humanely. There are plenty of other questions for your students to explore, including: • • • •

What makes the worm back up? Does the worm prefer the light or the dark? How much does the worm eat in a day? What kind of temperature does the worm prefer?

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Chapter 21

• What happens when the worm meets another worm? • What kind of soil does the worm prefer? • Does the worm prefer a smooth surface or a rough surface? All of these investigations can be done humanely. It’s fun and instructional for the students to design the investigations and work on keeping variables controlled. I must recommend a book to you that may help you and your students look at worms in a completely different way. It focuses on vermiculture—using worms to compost garbage. The book is called Worms Eat Our Garbage: Classroom Activities for a Better Environment (Appelhof, Fenton, and Harris 1993). It is full of ideas for keeping a colony of earthworms (a worm bin) in your classroom and watching garbage disappear and wonderful compost result. The format is classroom friendly with lots of activities for both younger and older students. My experience is that the most difficult aspect of studying worms is to overcome the reluctance of the teacher to have worms in the classroom. I must reassure you that the worms are really not a problem and if vegetable garbage is fed to the worms, there will be no odor whatsoever. If students learn to do the same at home, it could help take the strain off landfills, which would be wonderful for the environment. It demonstrates that recycling is friendly to the planet and promotes good ecological values in your students. In many areas, universities and schools are composting cafeteria garbage. With people throwing compostable food into landfills in plastic bags which will not decompose for decades, the idea of composting is an easy and valuable way for the common citizen to help the planet. Take the plunge!

Using the Story With Grades 5–8 Many of the ideas listed above are also valid for older students. Their questions

may be more sophisticated, but the worm remains the same and the investigations reward the students with valuable information. Since older students are often more familiar with thinking and planning investigations, they can get involved in more complex activities. For example, a very simple worm observation station can be built from 12" × 18" acrylic plastic sheets and 1" × 4" boards. It is similar to ant observation structures in that it is a narrow chamber filled with dirt so that the tunnels and activities of worms below the surface can be observed. The authors of Worms Eat Our Garbage recommend this structure (Appelhof, Fenton, and Harris 1993). The boards are cut into 12-inch pieces to be used as the side panels; the plastic sheets are fastened to these and then attached to a base made of another board cut to 18 inches. Soil is put into the space in the middle and worms added, along with some lettuce or vegetable garbage. Paper should be placed over the plastic sheeting when the worms are not being watched since they might react to the light and burrow deeper into the chamber, making observation difficult. If possible, observations should be done under dim light, which is not as disturbing to the worms.

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There are several great internet sites for more information on setting up a worm curriculum. One great example is from the University of Illinois in Urbana (www.urbanext.uiuc.edu/worms). The site also has a teachers’ bin with lots of suggestions for activities and a question-and-answer section about worms in the classroom. Finally, the site shows how to use a large jar covered with paper as an alternative worm observation device, for those who are put off by constructing the one described above. If you begin with the usual chart of what children already know about worms and move to the questions that result, there should be a great number of activities that can be designed and carried out by students. At this level, some of the questions might include • • • •

What kinds of soil does each kind of worm prefer? Do different kinds of worms choose different depths at which to live? What kinds of food do worms dispose of most? Which kinds of foods are eaten most quickly?

Designing investigations for these questions can interest students and probably generate more questions. Be prepared to let the investigations go on for a long time while you plan your curriculum. Most of these investigations can be carried out at home as well, with periodic reports from the investigators from time to time. You may well want to keep a worm bin in your classroom, as mentioned above in the K–4 section, for your students to see how well these animals recycle things that would ordinarily end up in the landfill. If your school is not already doing so, I encourage you to suggest a composting project for your school or district to your administrators. This project can prove to be a schoolwide science project and do a great deal of good for your community. Best of luck!

Related Books and Journal Articles Driver, R., A. Squires, P. Rushworth, and V. Wood-Robinson. 1994. Making

sense of secondary science: Research into children’s ideas. London and New York: Routledge-Falmer. Keeley, P. 2005. Science curriculum topic study: Bridging the gap between standards and practice. Thousand Oaks, CA: Corwin Press. Keeley, P., F. Eberle, and C. Dorsey. 2008. Uncovering student ideas in science: Another 25 formative assessment probes, volume 3. Arlington, VA: NSTA Press. Keeley, P., F. Eberle, and L. Farrin. 2005. Uncovering student ideas in science: 25 formative assessment probes, volume 1. Arlington, VA: NSTA Press. Keeley, P., F. Eberle, and J. Tugel. 2007. Uncovering student ideas in science: 25 more formative assessment probes, volume 2. Arlington, VA: NSTA Press.

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Chapter 21

References American Association for the Advancement of Science (AAAS). 1993. Benchmarks for science literacy. New York: Oxford University Press. Appelhof, M., M. F. Fenton, and B. L. Harris. 1993. Worms eat our garbage: Classroom activities for a better environment. Kalamazoo, MI: Flower Press. Cronin, D., and H. Bliss. 2003. Diary of a worm. New York: Scholastic Press. Konicek-Moran, R. 2008. Everyday Science Mysteries: Stories of inquiry-based science teaching. Arlington, VA: NSTA Press. National Research Council (NRC). 1996. National science education standards. Washington, DC: National Academies Press. University of Illinois Extension Service Internet. Herman the Worm. www. urbanext.uiuc.edu/worms.

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Chapter 22

What Did That Owl Eat?

E

nrique and Maria live in Miami, Florida, and love to visit the Everglades National Park at Shark Valley on the Tamiami Trail. It’s known for its wonderful variety of water birds and especially the alligators that sun themselves alongside the 24-kilometer (15-mile) trail that winds around the sawgrass prairie in the Everglades. Besides the alligators, there are great blue herons, great egrets, ibis, night

herons, anhingas, cormorants, grebes, and a lot of other birds that you can see right from the path that people walk on. There is a tram that drives around the loop and an announcer gives all the details about the park and its animals and plants. One beautiful day, Enrique and Maria were sitting under the chickee just outside the visitor’s center having a sandwich and drink. A chickee is a structure made of

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cypress tree poles and covered with sable palm leaves, put together by workmen from the Miccosukee Indian Tribe who live nearby. The chickee is a “house without walls,” a useful building for a semitropical climate like the Everglades. The chickee had benches for visitors to sit on to wait for the trams, eat lunch, or listen to programs given by the rangers and volunteers. Because the chickee had a palm roof and cypress beams high above the benches, it was an ideal place for a barred owl to build a nest up in the rafters. On this particular day, Enrique noticed a small gray object lying on the ground under the chickee roof. He picked it up using a tissue and looked at it. It was rather solid and Enrique thought that he saw some bones and some fur in it. Just about then, Shirley, a tram naturalist who knew just about everything about the Shark Valley area came over and asked, “What have you got there?” “I’m not sure,” said Enrique, “and neither is Maria. It was lying on the floor here and we wondered where it came from.” “I think what you have there is called an owl pellet,” said Shirley. “We have a barred owl family nesting directly above you and the owls drop their pellets out of the nest onto the floor. We find one about every day.” “You mean it’s owl poop?” asked Maria, who promptly dropped it onto the floor. “No, not at all,” said Shirley, “but it is a good idea that you handled it in a tissue since it might contain some germs that are not good for you. You see, owls eat their prey, usually mice or voles or even rats, whole. Inside the owl, the digestive juices dissolve the muscle parts of its prey but it doesn’t digest the hair and bones of the prey.” “You mean it just sits there in its stomach?” asked Enrique. “No,” replied Shirley. “The owl’s digestive system forms a mass of hair and bones that were not digested and the owl kind of spits it up and out its mouth. A lot of birds that eat their prey whole do the same thing, including grebes, cormorants, and herons.” “Yuck!” said Maria. “It’s owl vomit.” “Not really,” explained Shirley, “because the owl is not sick. It is just getting rid of the stuff it can’t digest. Maybe you have seen your cat cough up a hair ball. It’s a lot like that. In fact, if you take it apart carefully, you can find out what it has been eating. I wouldn’t do that with that one if I were you since it might have some mouse germs in it but if you sterilize it for 30 minutes, it might kill the germs.” “I think I’ll ask my teacher about it,” said Maria. “Maybe she has some or can get some we can take apart.” And do you know what? Maria’s teacher did have a way to get some owl pellets that were treated so that they were safe to take apart and see what was inside. And that is exactly what they did.

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Purpose This story is true, although Maria and Enrique are fictional characters. A barred

owl does live in the rafter of the chickee at Shark Valley and does drop owl pellets from its nest almost daily. The purpose of this story is twofold: (1) to learn more about the eating habits of owls and (2) to learn something about the anatomy of what the owls eat, which is mostly rodents. This is done by dissecting the owl pellet and trying to put together the bones found in the pellet into a complete skeleton.

Related Concepts • Skeletons • Diet • Predator-prey relationships

• Raptors • Ecology

Don’t Be Surprised Your students, just like Maria, may consider the pellet to be “owl poop” or “owl

vomit.” (Please note that scientists and naturalists refer to animal droppings as “scat.”) Pellets are not scat and are common in the predator bird world as a means of getting rid of indigestible materials such as feathers, fur, and bones. Since owls eat their small prey whole, it provides us with a great opportunity to find out what they eat and to be able to put together a puzzle of bones into an entire skeleton. This is not universal in the animal world. Some predator birds, such as certain hawks, do not eat their prey whole but rip it apart and dispose of the skeleton by carrying it out of the nest. Additionally, I have dissected the scat of the ever-present alligators in Shark Valley and, to my surprise, have never found anything beyond an occasional feather. Even though the alligator eats turtles, birds, small mammals, and fish whole, the alligator’s digestive system seems to absorb everything.

Content Background Several conditions combine to cause owls to produce pellets. They eat small prey,

have weak beaks for tearing their prey, and have no crop and weak acid in their digestive systems. Their food goes directly into a little pouchlike proventriculus, where digestion begins by means of enzymes and mucus, and then goes on to the gizzard since the owl has no crop for storing food. The gizzard has no enzymes or digestive juices, but grinds the prey into digestible size pieces that then pass into the intestines and are absorbed into the body. The gizzard retains the indigestible parts such as feathers, bones, and fur and compacts them into pellets that are later

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Chapter 22

regurgitated to the outside. Until this happens, the owl cannot eat again, since the pellet blocks the digestive system past the gizzard. Owls usually swoop down on their prey from a perch, using the soft feather structures of their wings to do so silently. The impact of the hit usually stuns the animal, and the owl’s talons may be sufficient to kill its prey immediately. But if the quarry is larger, the owl may be forced to kill it with its beak. Small animals can be eaten immediately, but larger prey may be taken back to a perch or even stored away for leaner times. Most often owls will end up back in the nesting area, which is why pellets are found on the forest floor underneath. Hawks, eagles, shorebirds, terns, herons, grebes, gulls, rails, shrikes, warblers, and swallows all are capable of regurgitating pellets if they eat their prey whole. These are hard to find since they do not usually regurgitate their pellets in the same place. If you find an owl pellet, it is a good idea to sterilize it by wrapping it in aluminum foil and putting it in a toaster oven at 300°F for 30 minutes before dissecting it. But the best solution is to invest in a set of owl pellets, skeleton charts, and instructions from a biological supply house. These pellets have been fumigated and should cause no problems unless a student is prone to allergies. Students should still wear gloves and possibly masks. The instructions usually call for spraying the pellet with a mist of water to soften it and make it easier to tear apart. Very often pellets from supply houses are collected in parts of the country other than that in which you teach. The origin of the pellets is usually included with the order so that you can tell where the pellets came from and possibly even what kind of owls produced them. The usual fare for owls is rats, mice, voles, and other rodents, plus an occasional earthworm or insect found near the owl’s territory. We have found shrew and blackbird skeletons as well. Since the owl’s digestive acid is so weak, skulls are usually present, which makes identification of the animals in the pellet easier. With older students, a magnified search of the pellet may even produce some setae from earthworms, but they would appear as little hairs, difficult to identify. Be sure to make it clear that you want identification sheets along with your order. An interesting fact is that another bird group, the grebes, swallow their own feathers on a regular basis and regurgitate them up as pellets periodically. The current theory is that the feathers delay the passage of small fish bones until they can be digested or at least padded by the feathers and then later regurgitated as pellets. Since grebes live and dive in the water, it is difficult to collect their pellets for analysis. Some researchers have been able to collect some, though, and have found fish bones encased inside. I sometimes refer to the use of feathers in this way as a kind of “birdie Pepto-Bismol.” The study of pellets is both interesting and instructive. The pellet reveals what the bird has been eating and perhaps a little about its ecosystem. The bones provide an opportunity for the students to assemble animal skeletons and to learn both the names of the bones as well as their functions.

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Related Ideas From the National Science Education Standards (NRC 1996) K–4: The Characteristics of Organisms

• Organisms have basic needs. For example animals need air, water, and food; plants require air, water, nutrients, and light. Organisms can survive only in environments in which their needs can be met. • The world has many different environments, and distinct environments support the life of different types of organisms. • Each plant or animal has different structures that serve different functions in growth, survival, and reproduction. • The behavior of individual organisms is influenced by external cues (such as a change in the environment).

K–4: Organisms and Environments

• All animals depend on plants. Some animals eat plants for food. Other animals eat animals that eat plants. • An organism’s patterns of behavior are related to the nature of that organism’s environment, including the kinds and numbers of other organisms present, the availability of food and resources and the physical characteristics of the environment.

5–8: Structure and Function in Living Systems

• Living systems at all levels of organization demonstrate the complementary nature of structure and function. Important levels of organization for structure and function include cells, organs, tissues, organ systems, whole organisms, and ecosystems.

5–8: Diversity and Adaptations of Organisms

• Millions of species of animals, plants, and microorganisms are alive today. Although different species might look dissimilar, the unity among organisms becomes apparent from an analysis of internal structures, the similarity of their chemical processes and the evidence of common ancestry.

Related Ideas in Benchmarks for Science Literacy (AAAS 1993) K–2: Diversity of Life

• Some animals and plants are alike in the way they look and in the things they do, and others are very different from one another.

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Chapter 22

• Plants and animals have features that help them live in different environments.

3–5: Diversity of Life

• A great variety of kinds of living things can be sorted into groups in many ways using various features to decide which things belong to which group. • Features used for grouping depend on the purpose of the grouping.

6–8: Diversity of Life

• Animals and plants have a great variety of body plans and internal structures that contribute to their being able to make or find food and reproduce.

Using the Story With Grades K–4 One main deterrent to using owl pellets with younger children is the “yuck” factor.

Many teachers demonstrate the dissection of the pellet before asking the children to do it. With very young children it may be enough to demonstrate the pellet and its contents as a group activity. The awe of seeing the bones in the pellet as they emerge can be as exciting to young children as it is to older children. Sometimes the students will ask to glue the pieces of the skeleton together so that it can be displayed. Since the bones are white, it is very effective to work on a piece of black or other dark-colored paper. First, tease the pellet into halves and then into quarters so that the fur can be separated from the bones within. You can use dissecting needles or toothpicks to pull the pellet apart. Children can use sharpened pencils if you decide to let them work directly with the pellets. It usually is more effective if children work in pairs so that one can record evidence while the other dissects the pellet. They should of course trade jobs so that each gets a turn dissecting. Some children may not want to touch the bones with bare hands so rubber (nonlatex) gloves should be used. For the students who do not want to use gloves, make sure that they wash their hands after they are finished and remind them every so often to keep their hands away from their faces. No real harm would probably come from touching their faces, but it is a good rule to stress whenever your students are doing lab work. An argument can be made for the use of safety glasses especially if your school requires them. However, it is a good practice to follow for any lab, and working with sharp pencils or toothpicks could accidentally cause eye damage. If any students are allergic to dust, they should also wear a face mask. Here one can also introduce the idea of a food chain with the children. “What did the vole eat?” (Probably an insect or a worm.) “What did the worm or insect eat?” (Probably plant material.) “Will anything eat the owl?” (Actually the owl is one of the top predators and has no natural enemies except humans, but their

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babies are vulnerable to foxes if they fall from the nest.) Sometimes snakes climb trees to eat babies or eggs, but they risk ending up as meals themselves if the adult discovers them. Students should realize that the energy from the Sun is being transferred from one organism to another as it passes up the chain since it begins with the stored energy in the bottom of all food chains, the plants.

Using the Story With Grades 5–8 There is usually no “yuck” factor here. In fact, I was once given the advice that

with middle schoolers, if all else fails, gross them out! The owl pellet is not gross but it borders on the edge enough that your students will probably take to them without hesitation. Most of the ideas previously described are appropriate for the upper grades. If your students get really interested in owls, you might arrange for a guide to take them “owling.” In this activity you go out about 10:00 p.m. into the woods and wait for an owl call or actual owl swooping down. Flashlights should be used at a minimum so as not to spook the owls or other animals. Actually, the best way to see any nocturnal animals is to go out about dusk and go into the woods and stand absolutely still. In no time at all, the floor of the forest will be alive with animal life. The trick is to stay still. Animals are spooked by motion, not by your presence or the color of your clothes. If you and your small group stand in a circle with everyone facing in, hands at shoulder height and watching straight ahead of them toward the outside of the circle, you will have all points of the compass covered. Any person can signal when they see something by raising a finger and the others should slowly turn their heads to look in the direction that person indicates. Once in the woods with a group, we were visited by a doe that stood just 5 meters (15 feet) away and looked at us for five minutes before moving slowly on. This investigation is also a wonderful opportunity to compare the skeletons of the rodents found in the pellet with the skeletal system of the human body. Many schools have a human skeleton that can be displayed along with the skeletons found in the pellet. Questions to ask are, What bones do we have in common? What bones are missing or different in the rodent? In the human? What value are the bones found in each to the animal’s survival? If it is possible to obtain a feather from a hawk and one from an owl, make them available to your students for comparison. What differences do they find in them and what are the advantages of these differences? The students usually find the owl feather to be much softer and realize that the form and function match here to provide the swooping owls a silent approach to their prey. Since they are mostly nocturnal, silence is of great importance.

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Chapter 22

Related Books and Journal Articles Driver, R., A. Squires, P. Rushworth, and V. Wood-Robinson. 1994. Making

sense of secondary science: Research into children’s ideas. London and New York: Routledge-Falmer. Keeley, P. 2005. Science curriculum topic study: Bridging the gap between standards and practice. Thousand Oaks, CA: Corwin Press. Keeley, P., F. Eberle, and C. Dorsey. 2008. Uncovering student ideas in science: Another 25 formative assessment probes, volume 3. Arlington, VA: NSTA Press. Keeley, P., F. Eberle, and L. Farrin. 2005. Uncovering student ideas in science: 25 formative assessment probes, volume 1. Arlington, VA: NSTA Press. Keeley, P., F. Eberle, and J. Tugel. 2007. Uncovering student ideas in science: 25 more formative assessment probes, volume 2. Arlington, VA: NSTA Press.

References American Association for the Advancement of Science (AAAS). 1993. Benchmarks for science literacy. New York: Oxford University Press. National Research Council (NRC). 1996. National science education standards. Washington, DC: National Academies Press.

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Chapter 23

Baking Bread

T

here aren’t a lot of things that smell better than fresh bread baking in the oven. It makes your mouth water and you dream of putting some fresh butter or jam on the warm bread, then enjoying a wonderful snack. MMMMM! Fresh bread is crusty on the outside, soft and tasty on the inside. At least that is what Rosa and Sofia were thinking as they looked at the new bread machine at

Grandma’s house where they were visiting one day after school. Grandma’s house usually smelled great every day because she was a baker of cookies, pies, and all sorts of fantastic things to eat. Today though, the adventure was to try out the new bread machine that she had received as a gift. It not only mixed the ingredients and kneaded the bread but it baked it too, all without any person touching the dough! All you had

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to do was to pour in the ingredients, then sit back and wait for the tasty treat to come out of the machine. Grandma used her usual recipe, which consisted of yeast, sugar, flour, salt, lukewarm water, and milk. After she had poured in the yeast, they closed the machine and sat back to let it do its work. Since it took a couple of hours, they played three games of scrabble. Then, when they heard the beep of the machine and smelled the delicious odor of the bread, they ran to the kitchen to check it out. Grandma pulled out the bread and laid it on the cutting board. But, wait! It didn’t look like bread at all. It resembled a brown brick! And it felt like one, too, when it had cooled enough to lift it. This was not what they had been waiting for and that’s for sure. “That machine is not very good if this is what it turns out,” said Sophia. “It’s a big disappointment if you ask me,” said Grandma. “I wonder what went wrong. I followed the directions every step of the way. I’ll tell you what—tomorrow, I’ll try again. You can come over to help me sample it. It has to work, or else it goes back!” The next day, they all watched as Grandma followed the directions and used the same ingredients from the cupboard she had used the day before. And lo and behold, the same disappointing brick emerged from the machine. “Okay, that’s it, the machine goes back,” said Grandma, “unless something else is wrong. Hmmm. I wonder if there could be some problem with the ingredients.” “What could be wrong with flour and water and milk and yeast?” asked Rosa. Grandma held her chin in the palm of her hand and said, “Well, the problem is that the bread did not rise. I think I know which ingredient might be the scoundrel! And we can find out which one, very easily.” So, Grandma checked the expiration dates on all of the ingredients and they used these data to design the experiment. The next day, the fresh strawberry jam tasted great on the light and fluffy bread from the machine.

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PURPOSE This story is meant to show students the importance of leavening agents in mak-

ing baked goods. Yeast, a living organism (a fungus), is necessary for baking risen yeast breads. This fungus can be ineffective if it is not healthy. The story will also give directions on proofing yeast so that the sad outcome described in the story is less likely to happen.

RELATED CONCEPTS • Fungi • Metabolism of living things

• Yeast • Chemical change and physical change

DON’T BE SURPRISED Your students may not be aware of the importance of leavening agents in the

preparation of baked goods. They may be familiar with the substance called yeast but not realize that it is a living organism and produces materials that are essential for the rising of baked goods by reacting with the sugars in the recipes to form carbon dioxide gas and alcohol. Being a living organism means that it has the needs of any living thing such as air, water, and warmth. Like all living organisms, it has a life cycle and therefore can die.

CONTENT BACKGROUND Baking bread is one of the most universal forms of food preparation. It dates back

to the earliest recorded history and probably existed before that. We have stories from the Old Testament about the Israelites being liberated from bondage and being so rushed that they were unable to take the time to allow leavening to take place in their bread. To commemorate that event, Jewish people today eat unleavened bread during the Passover holiday. Bread making probably goes back as far as the Stone Age where wild grass seeds were ground and mixed with liquids and baked on flat stones. Modern wheat, as we know it, has no direct wild antecedent and was probably created by selective breeding of several wild ancestors. It is hard to tell exactly when leavening was discovered to create bread in the shapes we find common today. But we do know that the Egyptians used leavening as long as 5,000 years ago. I confess to pondering a good deal about how these discoveries were made in the early years of civilization. For instance, who thought of eating the first raw oyster? I suspect that as people began to use wild animals and plants as food, some mistakes were made and some brave souls became very ill or even died from their toxins which provided valuable data for those who were not such brave souls. The history of food and agricultural production is fascinating, to say the least.

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Chapter 23

Leavening of baked products always involves the production of a gas, usually carbon dioxide. The bubbles of this gas expand during baking and cause what we call the “rising” of the bread dough. Yeast, a single-celled fungus called Saccharomyces cerevisiae, feeds on starches, which it first breaks down into simple sugars. As it digests these sugars, it produces carbon dioxide and alcohol. In the place of yeast in certain baking recipes, several other chemicals can be substituted. Baking soda is a naturally occurring chemical (sodium bicarbonate) that forms carbon dioxide when it comes in contact with a wet acid. So any recipe using baking soda must have some acid, like buttermilk or sour milk, in order for the carbon dioxide to form. Baking powder is a combination of baking soda and acid salts, so no other acidic ingredients are needed. Sourdough starter is a bacterium, the lactobacillus culture, mixed with yeast, which is more effective with the heavier rye flours. The bacteria feed off the products produced by the yeast, releasing carbon dioxide as well. You are probably familiar with the mixing of vinegar and baking soda to produce a bubbling chemical reaction, the perennially favorite “volcano” scenario of science fairs throughout history. Sometimes a chemical formula helps us to see the chain of events that occurs in a reaction. The chemical formula for this is as follows: CH3COOH (vinegar) + NaHCO3 (sodium bicarbonate-baking soda)  CH3COONa (sodium acetate) + H2CO3 (carbonic acid) That last product, carbonic acid, quickly decomposes into carbon dioxide and water: H2CO3  H2O + CO2 (becoming bubbles, which you see). Try mixing these two chemicals in a soda bottle, then swish them around and quickly place a deflated balloon on the bottle opening. The carbon dioxide will soon inflate the balloon. You can test for carbon dioxide by “pouring” the gas from the balloon onto a candle flame. The carbon dioxide will quickly put out the flame. When yeast encounters sugar in a warm environment, it becomes very hungry and immediately begins to ferment the sugar into alcohol and carbon dioxide. The balanced equation for this fermentation is: C6H12O6 (glucose)  2 C2H5OH (ethyl alcohol) + 2CO2 In other words, glucose is decomposed by the yeast into ethanol (ethyl alcohol) and carbon dioxide. The alcohol acts as a flavoring for the bread and the carbon dioxide helps to plump up the bread dough and it is said to “rise.” It is interesting to note that not all sugars react with yeast in the same way. Sucrose reacts best, fructose reacts a little bit, and lactose hardly reacts at all. The same process happens in fermenting alcoholic beverages, interacting with the sugars in the fruits or grains that are used. An interesting aside is that the historic figure John Chapman (known as Johnny Appleseed) knew about this process and planted orchards to lease to the pioneers as they traveled westward. The apples that grew on the trees he planted didn’t always produce apples that were good to eat. But, he knew that people in the 18th century did not prize apples for eating

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but instead, fermented the apple juice into alcoholic hard apple cider that was often safer than water to drink and provided them with the relaxation they sought. Even Puritans drank hard cider since there was no biblical admonition against apples, as there was against the fermented grape. All of these fermentation processes have the hallmarks of a chemical change taking place: New compounds are formed and the original components cannot be retrieved by physical means. Each of the original compounds is changed in the process and has no resemblance to its original form. Their physical and chemical properties have changed as well. It is important to the story that Grandma put in an ingredient that did not react properly in the baking of the bread. Bread that has risen has lots of sponginess, is less dense than flat bread and can be seen to have some spaces in its texture. The most likely suspect is that the yeast, which has a finite shelf life, may not have been viable, and so could not release the carbon dioxide that makes the bread rise. Grandma may also have put the yeast in water that was too hot. Yeast can be killed by temperatures over 40°C. Grandma and the girls can easily test by checking on the temperature of the water and by “proofing the yeast.” Proofing yeast is a technique used by most experienced bakers. A small amount of warm water, a little sugar and a package (or the equivalent) of yeast are placed in a container. In five minutes, if the yeast is good, bubbles will form on the surface of the mixture and can then be added to the flour and other ingredients. The problem of the bread machine “bricks” is solvable and rife with possible hypotheses that can be tested. I will go over some of these methods and hypotheses in the Using the Stories sections.

RELATED IDEAS FROM THE NATIONAL SCIENCE EDUCATION STANDARDS (NRC 1996) K–4: The Characteristics of Organisms

• Each plant or animal has different structures that serve different functions in growth, survival, and reproduction.

K–4: Properties of Objects and Materials

• Objects have many observable properties, including size, weight, shape, color, temperature, and the ability to react with other substances.

5–8: The Characteristics of Organisms

• Cells carry on the many functions needed to sustain life. They grow and divide thereby producing more cells. This requires that they take in nutrients, which they use to provide energy for the work that cells do and to make the materials that a cell or an organism needs.

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Chapter 23

5–8: Regulation and Behavior

• All organisms must be able to obtain and use resources, grow, reproduce, and maintain stable internal conditions while living in a constantly changing external environment.

5–8: Properties and Changes in Properties of Matter

• Substances react chemically in characteristic ways with other substances to form new substances (compounds) with different characteristic properties. In chemical reactions, the total mass is conserved.

RELATED IDEAS FROM BENCHMARKS FOR SCIENCE LITERACY (AAAS 1993) K–2: Cells

• Most living things need water, food, and air.

K–2: The Structure of Matter

• Things can be done to materials to change some of their properties, but not all materials respond the same way to what is done to them.

3–5: Cells

• Some living things consist of a single cell. Like familiar organisms, they need food, water, and air; a way to dispose of waste; and an environment they can live in.

3–5: The Structure of Matter

• When a new material is made by combining two or more materials, it has properties that are different from the original materials.

6–8: Cells

• Within cells, many of the basic functions of organisms—such s extracting energy from food and getting rid of waste—are carried out. The way in which cells function is similar in all living organisms.

6–8: The Structure of Matter

• Because most elements tend to combine with others, few elements are found in their pure form. • The temperature and acidity of a solution influences reaction rates. Many substances dissolve in water, which may greatly facilitate reactions between them.

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USING THE STORY WITH GRADES K–4 Cooking and baking appeals to kids of all ages because it is so much a part of their

everyday life. Grandma’s house always seems to be a magnet; particularly if she is prone to having cookies around and likes to have her grandchildren help with the baking. My grandmother always had a batch of cookies, either in the oven or in the special cookie jar. She didn’t have a bread machine and probably would have frowned at the idea of using one. She was a “from scratch” kind of person. Nevertheless, today’s children are used to electronic gadgets of all sorts so they might easily be familiar with the bread machine and its idiosyncrasies. But just as some children think that food appears magically in the market, the baking of bread in the home may be a rare event. I would like to mention at this point the existence of toy ovens known as EasyBake Ovens that have been around since the 1960s. They can be used in a classroom with relative safety. Their source of heat is a 100-watt bulb that is contained in a well-insulated box. Small containers of food can be baked in these ovens. The best part is that they are inexpensive and, though they have been around for over 50 years, are still available online or at most stores with toy departments. Your students can try baking bread in the classroom, albeit in small quantities dictated by the size of the oven and pans that it accommodates. Recipes abound on the internet and, I am sure, in the files of your students’ parents as well in your own kitchen. However, stores also sell mixes specifically for the Easy-Bake Oven, which I understand have mixed reviews (pardon the pun!). Other recipes will have to be cut to fit the size of the oven pans but this can be done easily. The probe “Is It Living?” from Keeley, Eberle, and Farrin (2005) might be informative for you in seeing what, in their environment, your students believe are “living.” With this information you can decide how you are going to use the yeast as an example of a living organism. If you use a yeast recipe, I suggest that you proof the yeast first by adding one tablespoon of white sugar to a half cup of water. The water should be at about 100°F or 40°C and no warmer or it will kill the yeast. It is best to use a thermometer to be sure. To this water, add the packet of yeast and wait for about five minutes. If the yeast is good, there will be froth or creamy foam on the surface. If not, throw it away and try another packet (and check the expiration date!). The yeast mixture then can be incorporated into your recipe in the appropriate amount and give a good rise to the bread. If you have a demonstration microscope with 400× magnification, you may be able to show your students the living yeast cells actually digesting the sugar and producing gas bubbles. They may also be able to see them budding, or reproducing asexually. It is a remarkable sight and will amaze even the youngest student. Remember, yeast often comes in a freeze-dried form and has to be rehydrated to restore it to its fully living form. If your students are old enough, you may want to try other leavening agents as called for in recipes. You can demonstrate the mixture of vinegar and baking soda to show them the release of the carbon dioxide. You may want to try the activity

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Chapter 23

mentioned earlier of placing a balloon over the top of a soda bottle with the soda/ vinegar mixture. This will also show your students that the carbon dioxide takes up space and has mass. Your students will probably have many suggestions about trying recipes with variations on the amounts and presence of ingredients. Happy baking!

USING THE STORY WITH GRADES 5–8 If you are not sure if your students have a reasonable understanding of what is

living and not, I suggest you give the probe “Is It Living?” by Keeley, Eberle, and Farrin (2005). This information will help you to decide how to proceed with the use of the living yeast and help students classify it as a living organism. Remember, yeast often comes in a freeze-dried form and has to be rehydrated to restore it to its fully living form. Most of the suggestions listed above in the K–4 section will also apply to middle school students. If they are capable of creating and understanding chemical equations, they might be taught to balance the equations. They can experiment with different amounts of leavening agents in beakers and describe and measure the results. There is one easy activity that can be used with baking soda and vinegar that helps students understand the physical concept of conservation of matter. Ask them if they can design an investigation to see if there is any weight loss or gain when the leavening agent and the acid are mixed. They can put the baking powder in the balloon, allowing them to put the balloon on the bottle top before the reaction starts, thus eliminating any gas loss. Since this is a closed system, the resulting chemical reaction will ensue and the end weight should be exactly the same as when all of the individual parts of the system were weighed prior to the reaction. In middle school, microscopes are often present so that the students can study the yeast reacting to the sugar water. Make a mixture of yeast and sugar in water just like in the proofing test. Once the froth has been on the top of the mixture for about 30 minutes, take a bit off and place it on a slide and, if possible, view it under approximately 400× magnification. Students should be able to see the yeast cells budding, that is, little buds forming on the parent cell. It is sometimes possible to see gas bubbles being formed as they go about digesting and converting the sugar to carbon dioxide and ethanol. Finally, I recommend the article in the journal Science Scope entitled “Bread Making: Biotechnology and Experimental Design” (Sitzman 2003). This article may fill in some of the gaps you may have in helping your students design experiments concerning yeast. The author suggests using what he calls “liquid bread,” which is all of the wet ingredients in the bread recipe. This can make things simpler for you in that you can experiment with excluding ingredients, such as sugar when you use yeast to show the need for it in the fermentation process. This is equivalent to proofing yeast except when you leave out the sugar, there is no frothing, and the appearance of frothing is your evidence of leavening. Leaving out the

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yeast or the sugar will result in a lack of the chemical reaction necessary for the rising of bread dough, which is easily seen in the “liquid bread.” Students may ask about the process called “kneading” which they see in pizza shops and anywhere that bread or bread products are made. The reason for kneading is to distribute the gases in the bread evenly in the dough so that the final product will be as homogeneous as possible. As you can see, the gas produced by leavening agents is a very important part of creating bread or breadlike products from the chemical reactions between the ingredients. You may also challenge your students to identify the process as one created by a chemical, not a physical change. Remember, the hallmark of a chemical change is that the final product cannot be undone and the individual ingredients cannot be recovered. Everyone will enjoy sampling the product of their investigations if you decide to carry it out to its completion. Happy baking!

RELATED BOOKS AND NSTA JOURNAL ARTICLES Keeley, P. 2005. Science curriculum topic study: Bridging the gap between standards

and practice. Thousand Oaks, CA: Corwin Press. Keeley, P., F. Eberle, and C. Dorsey. 2008. Uncovering student ideas in science, volume 3: Another 25 formative assessment probes. Arlington, VA: NSTA Press. Keeley, P., F. Eberle, and J. Tugel. 2007. Uncovering student ideas in science, volume 2: 25 more formative assessment probes. Arlington, VA: NSTA Press. Keeley, P., and J. Tugel. 2009. Uncovering student ideas in science, volume 4: 25 new formative assessment probes. Arlington, VA: NSTA Press. Konicek-Moran, R. 2008. Everyday science mysteries: Stories for inquiry-based science teaching. Arlington, VA: NSTA Press. Konicek-Moran, R. 2009. More everyday science mysteries: Stories for inquiry-based science teaching. Arlington, VA: NSTA Press. Konicek-Moran, R. 2010. Even more everyday science mysteries: Stories for inquirybased science teaching. Arlington, VA: NSTA Press.

REFERENCES Driver, R., A. Squires, P. Rushworth, and V. Wood-Robinson. 1994. Making sense of secondary science: Research into children’s ideas. London and New York: Routledge Falmer. Keeley, P., F. Eberle, and L. Farrin, L. 2005. Is it living? In Uncovering student ideas in science, volume 1: 25 formative assessment probes, 123–130. Arlington, VA: NSTA Press. Sitzman, D. 2003. Bread making: Biotechnology and experimental design. Science Scope 36 (5): 27–31.

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Chapter 23

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Chapter 24

Oatmeal Bugs

S

lam! Bang! Slam! “Where is that oatmeal?” thought Emma. “The cupboards are so full of things we don’t ever eat, I can’t find anything!” Emma pushed things around, took things out, and reshuffled the cupboard looking for the bright red and blue package of oatmeal.

Why oatmeal, you may ask? Well, Emma’s mom has the flu and when Emma asked her if she could do something to help, her mom said, “I would love some oatmeal and brown sugar. It is real comfort food when you have the flu. Would you make me some?” Of course she would. Making oatmeal was easy.

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Emma knew she had seen the oatmeal box in the cupboard and being a dutiful daughter was leaving no box unturned to find the stuff and cook it up for her mom. Finally, she moved a few boxes of cereal and lo and behold, there it was, tall and round and with the familiar face on it! The directions were easy she thought as she read them off the box lid. She opened the lid and poured out the white grainy oatmeal into a dish by way of the measuring cups and suddenly saw something move, all by itself. She peered at the oatmeal a little more closely and oops! There it was again, a little black buggy thing scooting around the grains of oatmeal. Then she saw something else—a little whitish, long, thin thing with legs up front was walking around in the oatmeal. There was also a black thing like the first one that looked dead, with no legs or anything. What was she going to tell her mom? She couldn’t serve her oatmeal with all of these things crawling around. Who knew how many more of them were in there? Well, she would just have to tell her mom that oatmeal was not on today’s menu. She would certainly understand given the circumstances. But what were these things? Three different kinds of intruders were in their cereal. Hmmmm. She poured the oatmeal back in the box and closed the lid and went to tell her mom the bad news. Maybe she could make her something else, like pancakes or waffles, if there were no things in those boxes, naturally. Perhaps her mom could give a clue to what they were later. Emma’s mom was very understanding and opted for a nice glass of orange juice and some dry cereal. Emma went back to the kitchen. Later on that day, when Emma’s mom felt well enough to come downstairs, they opened the oatmeal box and explored the contents of the box together. Okay, the little white thing was still crawling around but now the little dead looking thing was gone and there were two of the buggy looking things crawling around under the surface. Emma couldn’t find the dead looking thing but there was a little empty, black bug case that hadn’t been there before. Mysterious things were happening. Luckily, Emma’s mom was not squeamish and suggested that they keep the little beasts in a small jar with some oatmeal and keep track of them for a while. “Let’s see what we can find out by watching them,” she said. And so they did.

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Purpose Insects in the classroom are always interesting and easy to care for. Many people

have an aversion to insects or “bugs” as they call them. The mystery here has a lot to do with the life cycle of the insect in the cereal and what the various stages were that Emma found in the box. However, it is important that children get to know more about the most populous animals on our planet. It is important for them to understand their life cycles, their behavior, and the role they play within the Earth’s ecosystems. Some can be most destructive and yet without many of them we would have no fruit or many kinds of vegetables whose flowers they pollinate, no honey, no beautiful butterflies and moths, no food for many animals and plants, and no decomposing of animals and plants that die. From the pedagogical point of view insects invite inquiry into their behavior, their life cycles, and their adaptations to every climate and habitat known to humans. Get to know them— they are really cool!

Related Concepts • Life cycles • • • •

Classification of organisms Animal behavior Animal life Reproduction

• • • • •

Metamorphosis Insects Living things Adaptation Variation

Don’t Be Surprised Many students are afraid of insects and would rather step on them than study

them. They may believe that all insects bite and are harmful. They may also believe that the representative stages of the life cycle described in the story are different organisms. Also prevalent is the belief that only four-legged organisms with fur are animals, thus insects are not seen as animals. Another difficulty arises when children are asked to categorize animals into groups. They have to be helped to recognize that organisms with common characteristics are members of a common group and that in this particular case, beetles are related to bees, ants, butterflies, and other insects. By having students observe a life cycle, many of these conceptions can be modified.

Content Background “Bugs! Yuck!” This response is so common among humans. But without these

animals that make up well over a million different species, our world would not be the same.

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Chapter 24

We have chosen for the lead character in our story darkling beetles, Tenebrio molitor, more commonly known as “mealworms.” They are named for the larval stage where they look like grubs but are not since they have six legs and move easily through their grainy medium. They are not worms and their nickname, like so many common names, does not do justice to their lineage. Mealworms can be kept very easily in the classroom. The adult beetles do not fly so they can be kept in an open container in the classroom. Some teachers have kept their colonies for many years. Each child should be given a capped container with some oatmeal or cornmeal and a piece of raw potato or apple and a few beetles or larvae. The students’ job is to take care of them, let them out occasionally, and observe them. Plastic containers are best since they won’t shatter if dropped—and they will be! Access to magnifying glasses is helpful. Show the children how to hold the magnifier up to the eye and move the object to be viewed up to the eye until it is in focus. They will become enamored by the insects and over time will see the emergence of the larvae, the shedding of skin as the larvae eat and grow, and the pupa formation which darkens and finally is opened by the adult beetle and the life cycle is complete. I have seen this experience produce a complete change of students’ attitudes toward small animals with which they are not familiar. They have gone from stomping on them to studying them because of this experience of rearing a beetle and taking responsibility for their “pet.” You will want to acquire more information about this animal, and entering “Tenebrio” or “mealworms” into your favorite search engine will bring up many sites with information and more ideas for activities. Two of my favorites urls are www.thewildones.org/Curric/mealworm.html and www.enchantedlearning.com/ subjects/insects/beetles/mealworm/mealwormlifecycle.shtml, the first of which is an article reprinted from The Wild Times Teacher Connection and the second has a diagram of the Tenebrio life cycle. All in all, I believe you will enjoy the easily kept insect and the children’s response to it. I can almost guarantee a value change in students and teachers who are reluctant to work with “bugs” after they work with Tenebrio. I would caution you now that any inquiry directed at any living things in the classroom must be accompanied by a strictly enforced rule that no living thing should be harmed in any way as a result of the inquiry. The mealworm, Tenebrio, comes in two colors, black and yellow. They also can be purchased in two sizes, normal and giant. Do not purchase the enticing large sizes if you wish to do life cycle work. They are treated with a hormone that sometimes prevents them from going through their life cycle. Their energy goes into growing to a very large size but they may not undergo metamorphosis. They are fine for behavioral studies, however, and very easy to handle. Perhaps you will be able to find an old copy of the Elementary Science Study manual Teacher’s Guide for Behavior of Mealworms. It was first published in the late 1960s and is chock-full of great ideas on viewing and using mealworms for inquiry studies. If you cannot find an old copy of the manual, you can purchase one under the title of Animal

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Behavior from Delta Education. There are also a limited number of used copies of the Behavior of Mealworms listed in internet bookstores. For openers, I suggest that you do not tell the students the name of the animal. Strange as it seems, knowing the name of the mealworm sometimes seems enough for some students and their curiosity wanes. A great way to start with them is to play a little game invented by a former student of mine, Audubon director, Leonard Amburgy. The game is called, “What Can It Tell You and What Do You Want to Know?” After the children are given the larvae, they are asked to observe the animal and by observing it, find out what it is “telling you?” Only observations are allowed. Here children can be introduced to the difference between observations and inferences. Observations are strictly descriptions of what they have witnessed or observed. Inferences are an attempt to explain what they have seen. Examples: “The bug moves along the edge of the box,” is an observation. “The bug likes to feel a connection on its sides as it moves,” is an inference. Help the children stick to observations for the time being. Inferences will come later. List these on the “Our Best Thinking” chart and have the students put them into their science notebooks as well. Next, comes the part of the game called “What Do You Want to Know?” Here the students usually ask questions of the insect such as: What do you like to eat? Do you move backward, too? Do you like dark places or lighted places? How fast can you move? Do you always move in straight lines? These questions will become transformed into their predictions and eventual investigations. Once again issue the warning that no harm must come to the insect in the course of the investigation. “How long can you stay afloat before you drown?” is not an acceptable question. In the meantime, the children will be keeping track of their beetles in their containers and sooner or later the name of the beetle will emerge. They may even discover the life cycle from other sources and can then watch for the changes in their “pets.” The inquiry into the beetle’s life cycle and into its behavior patterns can go on for some time and it is not uncommon to see the activity continue, even in an informal way, for an entire school year. All revelations should be recorded on the “best thinking” chart and in the student science notebooks. You and your students may even discover some things about Tenebrio that are not found in books. They will teach you a great deal about insects if you let them. Tenebrio is a beetle because of its structure. It is a member of the phylum Arthropoda; that means animals with segmented bodies, exoskeletons, and jointed legs. This phylum includes crustaceans, spiders, mites, crabs, and so on. Within the phylum is the class Insecta, which includes all insects, which have all of the above characteristics and three pairs of segmented legs attached to the midsection of the body called the thorax. Insects’ three segments are head, thorax, and abdomen. Wings, when present, may be two or four and are also attached to the thorax. Beetles belong to the order Coleoptera that have a complete metamorphosis of egg, larva, pupa, and adult. Coleopterans have four wings; the top pair is usually hard and covers the entire thorax and abdomen. Other examples of Coleopterans are ladybugs, dung beetles, lightning bugs, and fireflies. The Tenebrio larvae and the adults are about 12–15 mm in length.

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Chapter 24

These beetles are harmless and do not bite or cause any discomfort to the person studying them. They seem to be comfortable being handled gently and have a life cycle that takes approximately a month at room temperature. Their preferred medium is meal or grains, with a piece of apple or potato for moisture. The apple or potato should be replaced periodically before it gets moldy. Mealworms can be purchased at local pet stores, where they are kept as food for lizards and other reptile pets. They can also be purchased at biological supply houses or on the internet. They are extremely inexpensive and you can easily start your own colony that can exist for years. They provide a highly visible example of an animal with a consistent and predictable life cycle and show all of the characteristics of a living animal. Again, I direct you to the previously mentioned websites for in-depth information on this insect and its classroom use. Even though some websites will offer lesson plans, I truly believe that the students’ questions will provide enough guidance for you to conduct real inquiry lessons for as long as you desire.

Related Ideas From THE National Science Education Standards (NRC 1996) K–4: The Characteristics of Organisms

• Organisms have basic needs. For example animals need air, water, and food: Plants require air, water, nutrients, and light. Organisms can survive only in environments in which their needs can be met. • The world has many different environments and distinct environments support the life of different types of organisms. • Each plant or animal has different structures that serve different functions in growth, survival, and reproduction. • The behavior of individual organisms is influenced by external cues (such as a change in the environment). Humans and other organisms have senses that help them detect internal and external cues.

K–4: Life Cycles of Organisms

• Plants and animals have life cycles that include being born, developing into adults, reproducing, and eventually dying. The details of this life cycle are different for different organisms. • Plants and animals closely resemble their parents.

K–4: Organisms and Environments

• All animals depend on plants. Some animals eat plants for food. Other animals eat animals that eat plants.

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• An organism’s patterns of behavior are related to the nature of that organism’s environment, including the kinds and numbers of other organisms present, the availability of food and resources and the physical characteristics of the environment.

5–8: Structure and Function in Living Systems

• Living systems at all levels of organization demonstrate the complementary nature of structure and function. Important levels of organization for structure and function include cells, organs, tissues, organ systems, whole organisms, and ecosystems.

5–8: Reproduction and Heredity

• Reproduction is a characteristic of all living systems: Because no individual organism lives forever, reproduction is essential to the continuation of every species. Some organisms reproduce asexually. Other organisms reproduce sexually.

5–8: Diversity and Adaptations of Organisms

• Millions of species of animals, plants and microorganisms are alive today. Although different species might look dissimilar, the unity among organisms becomes apparent from an analysis of internal structures, the similarity of their chemical processes and the evidence of common ancestry.

Related Ideas in Benchmarks for Science Literacy (AAAS 1993) K–2: Diversity of Life

• Some animals and plants are alike in the way they look and in the things they do, and others are very different from one another. • Plants and animals have features that help them live in different environments.

3–5: Diversity of Life

• A great variety of kinds of living things can be sorted into groups in many ways using various features to decide which things belong to which group. • Features used for grouping depend on the purpose of the grouping.

6–8: Diversity of Life

• Animals and plants have a great variety of body plans and internal structures that contribute to their being able to make or find food and reproduce. • For sexually reproducing organisms, a species comprises all organisms that can mate with one another to produce fertile offspring.

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Chapter 24

Using the Story With Grades K–4

Young children are usually fascinated with the little larvae that move quickly and in seemingly random directions. After hearing the story, they will have many ideas as to what the little critters in the story might be. Be sure to ask them for some reasons for their ideas. They should have the opportunity to give a reason or experience that supports their answer. With very young children you might decide to give them several larvae to keep in a container as described in the explanation section above. One first-grade teacher did this and allowed the life cycle to progress so that the children understood the concept of the cycle. Then she had them use what she called “biodrama” in which the children acted out the various stages of the life cycle of egg, larva, pupa, and adult. This added a kinesthetic aspect to their understanding. After this was obtained, she had them play the “What Does it Tell You and What Do You Want to Know?” game. The children were apprised of the meaning of observation and made a list of their observations on a chart and in their science notebooks. They were then allowed to ask questions of the larvae and the class worked together on designing experiments to find out the answers. In this way, the children were able to satisfy the Standards suggestions for inquiry as well as the suggestions about life cycles and behavior. I would like to refer you to two articles from Science and Children that might be of use to you in your teaching this topic: “Investigating Insects” by Janice Fay (2000) and “Meet the Mealworms” by Teena Staller (2005). They make good reading and provide some interesting ideas for extending the concept.

Using the Story With Grades 5–8 One way to open the class inquiry is to read the story and then ask the students

if they have any ideas as to what the bugs in the story were. These will be mostly guesses and then you can introduce them to Tenebrio by handing out a few larvae to each child or pair of children and asking them to observe them for a period of time. This is a good time to introduce them to the terms observe and infer. Ask them for their observations by playing part 1 of the game, “What Does it Tell You? Ask only for observations and this will give you some formative feedback as to their understanding the difference between the two terms. Write down the observations on a chart and have them put these into their science notebooks as well. When these observations have been verified, you can start part 2 of the game, “What Do You Want to Know?” If the children ask questions of the larvae directly, they can become more at ease with the process. Examples might be, “Do you like the dark better than the light?” Others might be, “How fast do you move?” “What do you like to eat?” These then have to be turned into hypotheses. Here you can put together the observations and the questions to form hypotheses. From their observations, the children may have an idea what the answers to their questions might be. Explain that an hypothesis is based on some knowledge and not just a

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wild guess. The above question about the preference of light or dark would then become a hypothesis such as, “Given a choice, the larvae will choose dark places rather than bright places.” This is testable and groups of children can explore how they will design a test. Once the class has critiqued these, the investigations can be carried out and the design, results, and conclusions can be recorded in the science notebooks. Since these animals are misnamed and are not worms at all, an article from Science Scope may be of interest to you as a means to extend the concept. “Mealworms, real worms?” (Dyche 1998) describes how one teacher allowed his students to compare mealworms with earthworms and discover the diversity in animals called “worms.” Also, NSTA published a book, The Pillbug Project: A Guide to Investigation, that uses a different animal but focuses on the same kinds of concepts.

Related Books and Journal Articles Barman, C., N. Barman, K. Bergland, and M. Goldston. 1999. Assessing stu-

dents’ ideas about animals. Science and Children 37 (1): 44–49. Burnett, R. 1999. The pillbug project: A guide to investigation. Arlington, VA: NSTA Press. Driver, R., A. Squires, P. Rushworth, and V. Wood-Robinson. 1994. Making sense of secondary science: Research into children’s ideas. London and New York: Routledge Falmer. Keeley, P. 2005. Science curriculum topic study: Bridging the gap between standards and practice. Thousand Oaks, CA: Corwin Press.

References American Association for the Advancement of Science (AAAS). 1993 Benchmarks for science literacy. New York: Oxford University Press. Dyche, S. E. 1998. Mealworms, real worms? Science Scope 22 (2): 19–23. Fay, J. 2000. Investigating Insects. Science and Children 38 (1): 26–30. National Research Council (NRC). 1996. National science education standards. Washington, DC: National Academies Press. Pope, L. 1997. Mealworms. The Wild Times Teacher Connection 2 (3). www.thewildones.org/Curric/mealworm.html. Staller, T. 2005. Meet the mealworms. Science and Children 42 (6): 28–31. Webster, D. 1966. Teacher’s guide for behavior of mealworms, elementary science study. Nashua, NH: Delta Education.

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Chapter 24

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Index

Index A A Framework for K–12 Science Education, ix A Private Universe, 5 “A Tasteful Story,” 189–198 concept matrix for, 41 content background for, 192–193 don’t be surprised about student thinking on, 191–192 purpose of, 191 related concepts for, 191 related ideas from Benchmarks for Science Literacy, 195–196 related ideas from National Science Education Standards, 194–195 story for, 189–190 thematic crossover between Uncovering Student Ideas in Science and, 13 using with grades 5–8, 197–198 using with grades K–4, 196–197 “About Me,” 20–21, 181–187 concept matrix for, 41 content background for, 184 don’t be surprised about student thinking on, 183 purpose of, 183 related concepts for, 41 related ideas from Benchmarks for Science Literacy, 185 related ideas from National Science Education Standards, 185 story for, 182 thematic crossover between Uncovering Student Ideas in Science and, 12 using with grades 5–8, 186–187 using with grades K–4, 186 Activities for Integrating Math and Science (AIMS) Educational Foundation, 129, 173, 178

Adaptation, 21, 41, 42 “Hitchhikers,” 139–147 “Oatmeal Bugs,” 237–245 “Trees From Helicopters,” 43–52 “Worms Are for More Than Bait,” 209–217 Algae: “Looking at Lichens,” 79–89 Alternative conceptions, 4. See also Misconceptions of students Amburgy, Leonard, 241 American Association for the Advancement of Science (AAAS), 2, 93 Animal behavior “Oatmeal Bugs,” 237–245 “Worms Are for More Than Bait,” 209–217 Animal Behavior, 240–241 Asberry, Karen, 155 Attenborough, David, 68 Ausubel, David, 10

B “Baking Bread,” 227–235 concept matrix for, 42 content background for, 229–231 don’t be surprised about student thinking on, 229 purpose of, 229 related concepts for, 229 related ideas from Benchmarks for Science Literacy, 232 related ideas from National Science Education Standards, 231–232 story for, 227–228 thematic crossover between Uncovering Student Ideas in Science and, 13 using with grades 5–8, 234–235 using with grades K–4, 233–234

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Barber, J., 29 Behavior of Mealworms, 241 Benchmarks for Science Literacy, 2 story connections to, 13, 26 “A Tasteful Story,” 195–196 “About Me,” 185 “Baking Bread,” 232 “Dried Apples,” 123 “Flowers: More Than Just Pretty,” 72–73 “Halloween Science,” 154–155 “Hitchhikers,” 144–145 “In a Heartbeat,” 167 “Looking at Lichens,” 86–87 “Oatmeal Bugs,” 243 “Plunk, Plunk,” 132–133 “Reaction Time,” 205–206 “Seed Bargains,” 105–106 “Seedlings in a Jar,” 97–98 “Springtime in the Greenhouse,” 114–115 “The Trouble With Bubble Gum,” 175–176 “Trees From Helicopters,” 49 “Trees From Helicopters, Continued,” 59–60 “What Did That Owl Eat?”, 223–224 “Worms Are for More Than Bait,” 214 Botany “Dried Apples,” 119–125 “Flowers: More Than Just Pretty,” 65–77 “Halloween Science,” 149–158 “Hitchhikers,” 139–147 “Looking at Lichens,” 79–89 “Plunk, Plunk,” 127–136 “Seed Bargains,” 101–108 “Seedlings in a Jar,” 91–100 “Springtime in the Greenhouse,” 109–117 “Trees From Helicopters,” 43–52 “Trees From Helicopters, Continued,” 53–62 Bravo, M., 29

C Campbell, Brian, 31 Cervetti, G. N, 29 Circulatory system: “In a Heartbeat,” 161–170 Common sense science, 5, 6 Communication skills, 28–30

Concept matrix for stories, 10, 14, 41–42 Constructivism, 5, 31 Content curriculum guide, using book as, 17–23

D Data collection and recording, 33–34 Discourse of science, 29, 30 Discrepant events, 7, 191 “Dried Apples,” 20–21, 119–125 concept matrix for, 41 content background for, 121–122 don’t be surprised about student thinking on, 121 purpose of, 121 related concepts for, 121 related ideas from Benchmarks for Science Literacy, 123 related ideas from National Science Education Standards, 123 story for, 119–120 thematic crossover between Uncovering Student Ideas in Science and, 12 using with grades 5–8, 124–125 using with grades K–4, 123–124 Duckworth, Eleanor, 2, 4

E Easy-Bake Oven, 233 Eberle, F., 10, 233, 234 English language learners (ELLs), 28, 30, 34–36, 129, 156 Entomology: “Oatmeal Bugs,” 237–245 Evaporation, 19, 21 “Dried Apples,” 41, 119–125 Everglades National Park Python Project, 34 Everyday Science Mysteries, xi, 17, 19, 115 “Where Are the Acorns?” story from, xi–xii teacher uses of, xii–xvi “Everyday Science Mystery Readers Theater,” 24–25 Experiments, 1, 4 controlling variables in, 1 critical, 1–2 design of, 33

F Fair test, xii, 1, 29, 103, 134, 194, 196, 207 Farrin, L., 233, 234

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Fay, Janice, 244 5E inquiry method, xiv–xv “Flowers: More Than Just Pretty,” 65–77 concept matrix for, 41 content background for, 67–70 don’t be surprised about student thinking on, 67 purpose of, 67 related concepts for, 67 related ideas from Benchmarks for Science Literacy, 72–73 related ideas from National Science Education Standards, 71–72 story for, 66 thematic crossover between Uncovering Student Ideas in Science and, 11 using with grades 5–8, 75–77 using with grades K–4, 74–75 Fulton, Lori, 31 Fungi “Baking Bread,” 227–235 “Looking at Lichens,” 79–89

G Germination, 42 “Plunk, Plunk,” 127–136 “Seed Bargains,” 101–108 “Seedlings in a Jar,” 91–100 “Springtime in the Greenhouse,” 109–117 “Trees From Helicopters,” 43–52

H “Halloween Science,” 147, 149–158 concept matrix for, 42 content background for, 151–153 don’t be surprised about student thinking on, 151 purpose of, 151 related concepts for, 151 related ideas from Benchmarks for Science Literacy, 154–155 related ideas from National Science Education Standards, 153–154 story for, 149–150 thematic crossover between Uncovering Student Ideas in Science and, 12 use as interactive inquiry play, 25 using with grades 5–8, 157–158 using with grades K–4, 155–157 Hands-on, minds-on investigations, 3, 4,

9, 28. See also Inquiry-based science Hazen, Robert, 10 Heredity: “About Me,” 181–187 “Hitchhikers,” 139–147 concept matrix for, 42 content background for, 141–143 don’t be surprised section for, 141 purpose of, 141 related concepts for, 141 related ideas from Benchmarks for Science Literacy, 144–145 related ideas from National Science Education Standards, 143–144 story for, 139–140 thematic crossover between Uncovering Student Ideas in Science and, 12 using with grades 5–8, 147 using with grades K–4, 145–147 Homeschool programs, 26 Human physiology “A Tasteful Story,” 189–198 “About Me,” 181–187 “In a Heartbeat,” 161–170 “Reaction Time,” 201–208 Hypothesis formulation and testing, 1, 3, 4

I “In a Heartbeat,” 161–170 concept matrix for, 42 content background for, 163–166 don’t be surprised about student thinking on, 163 purpose of, 163 related concepts for, 163 related ideas from Benchmarks for Science Literacy, 167 related ideas from National Science Education Standards, 166–167 story for, 161–162 thematic crossover between Uncovering Student Ideas in Science and, 12 using with grades 5–8, 169–170 using with grades K–4, 167–169 Inquiry and the National Science Education Standards: A Guide for Teaching and Learning, 22 Inquiry-based science, 2–3 definition of, 15 essential elements of, 2 firsthand, 29 literacy and, 28–30

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Index

providing help to students during, 32–34 science notebooks and, 30–32 Inventing Density, 2 Investigations, 1, 4 hands-on, minds-on, 3, 4, 9, 28 secondhand, 29

J Joyce, James, 27

K Keeley, Page, 10, 99, 233, 234 Konicek, Richard D., 18

L Lab reports, 31 Language, 28–30. See also Vocabulary development Learning constructivist theory of, 5, 31 cooperative, 32 mental models and, 5–6 Life cycles, 42 “Hitchhikers,” 139–147 “Looking at Lichens,” 79–89 “Oatmeal Bugs,” 237–245 “Seed Bargains,” 101–108 “Springtime in the Greenhouse,” 109–117 “Trees From Helicopters,” 43–52 “Trees From Helicopters, Continued,” 53–62 “Worms Are for More Than Bait,” 209–217 Linking Science and Literacy in the K–8 Classroom, 28 Literacy and science, 27–30. See also Vocabulary development “Looking at Lichens,” 79–89 concept matrix for, 42 content background for, 81–85 don’t be surprised about student thinking on, 81 purpose of, 81 related concepts for, 81 related ideas from Benchmarks for Science Literacy, 86–87 related ideas from National Science Education Standards, 85–86 story for, 80 thematic crossover between Uncovering

Student Ideas in Science and, 11 using with grades 5–8, 88–89 using with grades K–4, 87–88

M Making Sense of Secondary Science: Research Into Children’s Ideas, 10 Martin, K., 7 Mealworms: “Oatmeal Bugs,” 237–245 Mental models, 5–6 Metacognition, xv, 3, 23, 29, 31 Miller, E., 7 Misconceptions of students, 2, 23, 24, 28 challenging of, 6 mental models and, 5–6 in stories, 4–5 uncovering of, 2, 10 (See also Uncovering Student Ideas in Science) More Everyday Science Mysteries, 115 Morgan, Emily, 155 Muth, K. D., 29

N National Research Council (NRC), ix, 2–3, 19 National Science Education Standards (NSES), xii, xiv, 2 story connections to, 13, 26 “A Tasteful Story,” 194–195 “About Me,” 185 “Baking Bread,” 231–232 “Dried Apples,” 123 “Flowers: More Than Just Pretty,” 71–72 “Halloween Science,” 153–154 “Hitchhikers,” 143–144 “In a Heartbeat,” 166–167 “Looking at Lichens,” 85–86 “Oatmeal Bugs,” 242–243 “Plunk, Plunk,” 131–132 “Reaction Time,” 205 “Seed Bargains,” 104–105 “Seedlings in a Jar,” 95–96 “Springtime in the Greenhouse,” 112–113 “The Trouble With Bubble Gum,” 174–175 “Trees From Helicopters,” 48–49 “Trees From Helicopters, Continued,” 58 “What Did That Owl Eat?”, 223

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“Worms Are for More Than Bait,” 213–214 National Science Teachers Association (NSTA), 10, 14, 15, 116, 117, 245 Nature of science, 24, 30, 170 Nervous system “A Tasteful Story,” 189–198 “Reaction Time,” 201–208 NSTA Reports, 15

O “Oatmeal Bugs,” 214, 237–245 concept matrix for, 41 content background for, 239–242 don’t be surprised about student thinking on, 239 purpose of, 239 related concepts for, 239 related ideas from Benchmarks for Science Literacy, 243 related ideas from National Science Education Standards, 242–243 story for, 237–238 thematic crossover between Uncovering Student Ideas in Science and, 13 using with grades 5–8, 244–245 using with grades K–4, 244 Oral hygiene: “The Trouble With Bubble Gum,” 171–178 “Our Best Thinking” chart, 60, 74, 124, 146, 215, 241 Owl pellets: “What Did That Owl Eat?”, 219–225

P Padilla, Michael, 15, 29 Padilla, R. K., 29 Pearson, P. D., 29 Photosynthesis, 42 “Seedlings in a Jar,” 91–100 “Springtime in the Greenhouse,” 109–117 “Plunk, Plunk,” 127–136 concept matrix for, 42 content background for, 129–131 don’t be surprised about student thinking on, 129 extension story for, 135–136 content background for, 136 purpose of, 129 related concepts for, 129

related ideas from Benchmarks for Science Literacy, 132–133 related ideas from National Science Education Standards, 131–132 story for, 127–128 thematic crossover between Uncovering Student Ideas in Science and, 12 using with grades 5–8, 135 using with grades K–4, 133–135 Pollan, Michael, 46 Postman, N., 29 Preconceptions, 1–2, 3, 5, 6, 10, 13, 32, 50, 51, 117, 187. See also Misconceptions of students Predictions, 1, 4, 29 Primarily Plants, 129 Problem solving, xv, 32, 33, 35 Pumpkin science: “Halloween Science,” 149–158

R “Reaction Time,” 201–208 concept matrix for, 42 content background for, 203–204 don’t be surprised about student thinking on, 203 purpose of, 203 related concepts for, 203 related ideas from Benchmarks for Science Literacy, 205–206 related ideas from National Science Education Standards, 205 story for, 201–202 thematic crossover between Uncovering Student Ideas in Science and, 13 using with grades 5–8, 207–208 using with grades K–4, 206–207 Reading skills, 28–30 Reading stories to children, 32 Real-life applications, 1, 4, 9 Reiss, Michael J., 27 Reproduction “Flowers: More Than Just Pretty,” 65–77 “Hitchhikers,” 139–147 “Looking at Lichens,” 79–89 “Oatmeal Bugs,” 237–245 “Trees From Helicopters,” 43–52 “Trees From Helicopters, Continued,” 53–62 “Worms Are for More Than Bait,” 209–217

251 Everyday life Science Mysteries Copyright © 2013 NSTA. All rights reserved. For more information, go to www.nsta.org/permissions.

Index

S School Science Review, 27 Science and Children, 74, 155, 244 Science Curriculum Topic Study, 10, 13 Science Education, 3 Science Matters: Achieving Scientific Literacy, 10 Science methods courses for teacher preparation, using book for, 23–24 Science notebooks, 30–32 difference from science journals and science logs, 31 lab reports and, 31 recording data in, 33–34 use with stories, 31 Science Notebooks: Writing About Inquiry, 31 Science Scope, 106, 158, 234, 245 Science talk, 28–30 Science teaching strategies, 2–3 Scientific explanations, 2, 3 Scientific ideas, 5–6 Scientific literacy, 27–28 Scientific method, 33 Scientific principles, ix, 28 “Seed Bargains,” 20–21, 101–108, 115 concept matrix for, 41 content background for, 104 don’t be surprised about student thinking on, 103 purpose of, 103 related concepts for, 103 related ideas from Benchmarks for Science Literacy, 105–106 related ideas from National Science Education Standards, 104–105 story for, 101–102 thematic crossover between Uncovering Student Ideas in Science and, 12 using with grades 5–8, 107–108 using with grades K–4, 106–107 Seed dispersal: “Hitchhikers,” 139–147 “Seedlings in a Jar,” 4, 91–100 concept matrix for, 42 content background for, 93–95 don’t be surprised about student thinking on, 93 purpose of, 93 related concepts for, 93 related ideas from Benchmarks for Science Literacy, 97–98 related ideas from National Science

Education Standards, 95–96 story for, 91–92 thematic crossover between Uncovering Student Ideas in Science and, 12 using with grades 5–8, 99–100 using with grades K–4, 98–99 Senses: “A Tasteful Story,” 189–198 Shapiro, Bonnie, 2 Snow, Skip, 34 Solving the teacher, 2, 4 “Springtime in the Greenhouse,” 4–5, 109–117 concept matrix for, 42 content background of, 111–112 don’t be surprised about student thinking on, 111 purpose of, 111 related concepts for, 111 related ideas from Benchmarks for Science Literacy, 114–115 related ideas from National Science Education Standards, 112–113 story for, 110 thematic crossover between Uncovering Student Ideas in Science and, 12 using the story with grades 5–8, 116– 117 using the story with grades K–4, 115– 116 Staller, Teena, 244 Sterling, Donna, 158 Stories, 3–5 books and NSTA journal articles related to, 14 complementary books to use with, 10 concept matrix for, 10, 14, 41–42 content background for, 11 don’t be surprised about student thinking on, 11 materials for, 14 organization of, 10–14 purpose of, 10 rationale for, 6–7 reading to children, 32 real-life applications of, 1, 4, 9 references for, 14 related concepts for, 11 related ideas from National Science Education Standards and Benchmarks for Science Literacy, 13

252 N at io nal Science Teachers Asso ciatio n Copyright © 2013 NSTA. All rights reserved. For more information, go to www.nsta.org/permissions.

relevance of, 9–10 science notebooks and, 31 thematic crossover between Uncovering Student Ideas in Science and, 11–13 topics of, 4, 6 use as content curriculum guide, 17–23 use as interactive inquiry plays, 24–25 use in homeschool programs, 26 use in science methods courses for teacher preparation, 23–24 using with grades K–4 and grades 5–8, 13–14 Sykes, Erin, 158 Symbiosis: “Looking at Lichens,” 79–89 Systems, 19, 21, 41, 42 open vs. closed, 94 “Seedlings in a Jar,” 91–100

T Teacher’s Guide for Behavior of Mealworms, 240 The Botany of Desire, 46 The Pillbug Project, A Guide to Investigation, 245 The Private Life of Plants, 69 “The Trouble With Bubble Gum,” 171– 178 concept matrix for, 42 content background on, 173–174 don’t be surprised about student thinking on, 173 purpose of, 173 related concepts for, 173 related ideas from Benchmarks for Science Literacy, 175–176 related ideas from National Science Education Standards, 174–175 story for, 172 thematic crossover between Uncovering Student Ideas in Science and, 12 using with grades 5–8, 177–178 using with grades K–4, 176–177 The Wild Times Teacher Connection, 240 Time requirements, 1 “Trees From Helicopters,” 20–21, 43–52, 58 concept matrix for, 41 content background for, 45–48 don’t be surprised section for, 45 purpose of, 45

related concepts for, 45 related ideas from Benchmarks for Science Literacy, 49 related ideas from National Science Education Standards, 48–49 story for, 43–44 thematic crossover between Uncovering Student Ideas in Science and, 11 using with grades 5–8, 51–52 using with grades K–4, 50–51 “Trees From Helicopters, Continued,” 53–62, 77 concept matrix for, 41 content background for, 55–58 don’t be surprised about student thinking on, 55 purpose of, 55 related concepts for, 55 related ideas from Benchmarks for Science Literacy, 59–60 related ideas from National Science Education Standards, 58 story for, 54 using with grades 5–8, 61–62 using with grades K–4, 60–61 Trefil, James, 10 Tugel, J., 10, 99

U Ulysses, 27 Uncovering Student Ideas in Science: 25 Formative Assessment Probes, 10, 32, 50, 51, 60, 106, 107, 145, 164, 186–187 thematic crossover between stories and, 11–13

V Van Helmont, Jan Baptista, 94 Vocabulary development, 29, 31, 99, 110 with English language learners, 34–35 by reading stories to children, 32

W West, Donna, 106, 107 “What Can It Tell You and What Do You Want to Know?” strategy, 215, 241, 244 What Children Bring to Light, 2 “What Did That Owl Eat?”, 219–225 concept matrix for, 41

253 Everyday life Science Mysteries Copyright © 2013 NSTA. All rights reserved. For more information, go to www.nsta.org/permissions.

Index

content background for, 221–222 don’t be surprised about student thinking on, 221 purpose of, 221 related concepts for, 221 related ideas from Benchmarks for Science Literacy, 223–224 related ideas from National Science Education Standards, 223 story for, 219–220 thematic crossover between Uncovering Student Ideas in Science and, 13 using with grades 5–8, 225 using with grades K–4, 224–225 Winokur, Jeffrey, 28 Wisconsin Fast Plants, 76, 187 “Worms Are for More Than Bait,” 209–217 concept matrix for, 41 content background for, 211–213 don’t be surprised about student thinking on, 211 purpose of, 211 related concepts for, 211 related ideas from Benchmarks for Science Literacy, 214

related ideas from National Science Education Standards, 213–214 story for, 210 thematic crossover between Uncovering Student Ideas in Science and, 13 using with grades 5–8, 216–217 using with grades K–4, 215–216 Worms Eat Our Garbage: Classroom Activities for a Better Environment, 216 Worth, Karen, 28 Writing in science, 28, 30 of an everyday science mystery, 24 lab reports, 31 science notebooks, 30–32

Y Yeast: “Baking Bread,” 227–235

Z Zoology “Oatmeal Bugs,” 237–245 “What Did That Owl Eat?”, 219–225 “Worms Are for More Than Bait,” 209–217

254 N at io nal Science Teachers Asso ciatio n Copyright © 2013 NSTA. All rights reserved. For more information, go to www.nsta.org/permissions.

Everyday life Science Mysteries

STORIES FOR INQUIRY-BASED SCIENCE TEACHING

How do tiny bugs get into oatmeal? What makes children look like—or different from—their parents? Where do rotten apples go after they fall off the tree? By presenting everyday mysteries like these, this book will motivate your students to carry out hands-on science investigations and actually care about the results. These 20 open-ended mysteries focus exclusively on biological science, including botany, human physiology, zoology, and health. The stories come with lists of science concepts to explore, grade-appropriate strategies for using them, and explanations of how the lessons align with national standards. They also relieve you of the tiring work of designing inquiry lessons from scratch.

STORIES FOR INQUIRY-BASED SCIENCE TEACHING

“What makes this book so special is the unique way science is integrated into the story line, using characters and situations children can easily identify with.”—Page Keeley, author of the NSTA Press series Uncovering Student Ideas in Science

PB333X2 ISBN: 978-1-936959-30-3

Grades K–8

Copyright © 2013 NSTA. All rights reserved. For more information, go to www.nsta.org/permissions.