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3 Foundational Knowledge and Conceptual Change Recent research has revolutionized views of how childrenâs minds develop from infancy through adolescence. The past 20 to 30 years of research have shown that children come to school with a great capacity for learning in general and learning science in particu- lar. Even preschool children have a rich set of ideas, conceptual frameworks, and reasoning skills. They bring to school rudimentary âtheories,â1 rules of thumb, and general principles that help them separate the world into different domains and organize their expectations about how things ought to behave. Their under- standing of the world helps them explain phenomena and solve problems. They are able to engage in surprisingly sophisticated scientific thinking in the early grades and can appreciate deep points about the nature of science. This is good news for educators committed to improving science learning for students. It also raises a number of questions that are explored throughout this book: â¢ How does one recognize the knowledge that children bring to school? â¢ How does one build on this knowledge in ways that specifically support science learning? â¢ How does one make diversity (in culture, language, or prior experience) a resource rather than an obstacle? â¢ How does one integrate the four strands of science learning so that each informs and enhances the others? Elements of all four strands of science learning can be seen in the capabili- ties and knowledge that children bring with them to school. This means that the four-strand framework described in Chapter 2 can and should begin as soon as 37
children enter school. In this chapter, we focus on the first strand, understanding scientific explanations, by looking at the concepts (and alternate conceptions) that students bring to school. These concepts evolve as students move from kindergarten through eighth grade as a result of instruction, experience, and maturation. A key challenge for teachers is to build on studentsâ embodied knowledge and understanding of the world and to help them confront their misconceptions productively in order to develop new understanding. Identifying a Shared Base of Understanding in Young Children Children in all cultures encounter and learn about a common set of natural systems or science âdomains.â Four domains have been extensively studied in infants and young children, and these domains loosely connect to scientific dis- ciplines: simple mechanics of solid bounded objects (naÃ¯ve physics), behaviors of psychological agents (naÃ¯ve psychology), actions and organization of living things (naÃ¯ve biology), and makeup and substance of materials (naÃ¯ve chemistry). These domains provide solid foundations on which children can build scientific knowl- edge and skill. Young children tend to think about their experiences in regard to each domain in similar ways, regardless of their culture, so one can expect that nearly all chil- dren will share basic ideas and expectations about these domains. In biology, for example, they correctly identify living and nonliving things and understand that species âfitâ biological niches that serve their survival needs. Four Domains of Knowledge These are just a few examples of the fairly broad basic under- 1. Simple mechanics of solid bounded objects standing that young children 2. Behaviors of psychological agents derive from their experience in 3. Actions and organization of living things the world even before formal instruction begins. 4. Makeup and substance of materials Interestingly, while all children tend to reason in a given domain in similar ways, the type of reasoning they do varies by domain, depending on how the domain functions. That is, their reasoning is domain 38 Ready, Set, SCIENCE!
specific. For example, in physics, children observing a rolling ball understand that the ball has no âdesireâ to roll down a ramp and that when it hits a wall it doesnât âwantâ to hit the wall. In contrast, in the psychological domain, children do think a person or animal might have the desire to go down a ramp in order to find food at the bottom or that a person might want to hit a wall because she is angry. Children understand that the causes of physical events are fundamentally different from the causes of psychological events. Another example of this domain-specific reasoning can be observed in the questions children often ask about living things, in contrast to the questions they ask about manufactured objects. In studies, the questions they ask vary systemati- cally. Children know to ask what a tool, such as a wrench, is used for. They recog- nize that tools, like many other manufactured objects, often have a purpose. They also recognize that living things, such as tigers, donât have the same practical pur- pose as tools. Their questions about living things therefore do not usually focus on what the living thing is used for or what its purpose is. This pattern of thinking or applying reasoning in a consistent way within a domain of knowledge but in different ways across domains of knowledge seems to hold true regardless of a childâs culture or language. Recognizing that virtually all children arrive at school with these types of sophisticated reasoning skills and knowledge is the first step toward building on and supporting effective, ongoing science learning. Besides their conceptual understanding of the world, children bring to school a variety of general reasoning abilities that can form the underpinnings of scientific reasoning. Preschoolers can be exquisitely sensitive to abstract patterns in the world, and they can use this sensitivity to guide how they think about the behaviors of objects, the nature of living things, the layout of things in space, and many other ideas. For example, young children and even preverbal infants seem to have a strong sense of the principles of cause and effect that goes beyond merely noticing that two things happen together. They have reasonable expectations about how causes precede effects and how certain kinds of causes are linked to specific kinds of effects. Categorization, induction, and many other forms of rea- soning seem to be guided by such abstract forms of information. The foundations of modeling are also evident in young children. Long before they arrive at school, children have some appreciation of the representational quali- ties of toys, pictures, scale models, and video representations. In pretend play, chil- dren may treat one object as a stand-in for another (a block for a teacup; a banana for a telephone), yet they still understand that the object has not really changed its Foundational Knowledge and Conceptual Change 39
original identity, character, or function. Later in school, they build on similar under- standing to use counters to solve simple early arithmetic problems. Young childrenâs use of models has been validated in a series of laboratory- based studies. In studies by Deloache and colleagues, children as young as three years old are presented with both an actual room and a scale model of that room. They are shown where an object resides in the scale model room and then asked to find the object in the actual room. To be successful in this task children must understand that the model is an object in its own right and that it represents something about the larger room. This suggests that children have rudimentary skills for modelingâa fun- damental aspect of contemporary scientific practiceâeven before kindergarten. In addition, children are able to understand their own and othersâ ideas, beliefs, and knowledge, and they have the ability to assess sources of knowledge. The ability to consider ideas and beliefs as separate from the material world is essential for children to engage in debates about the interpretation of evidence. Children also understand that knowledge is distributed unevenly in the world. Before they arrive at school they already have a sense of who has expertise in areas they care about and who does not. This too is critical to scientific practice, as much of science is done in groups, and both scientists and science learners have varying levels of expertise. Finally, children are eager participants in the quest for knowledge. One of the great pleasures of working with young children is their enthusiasm and lack of inhibition in generating and considering new Young children begin school withâ¦ ideas. They discuss ideas and debate positions with a sophistication that is often surprising. â¢ rich knowledge of the natural world. Even very young children can engage in all â¢ the ability to reason. four strands of scientific proficiency. They typi- cally have significant gaps in their understanding â¢ an understanding of the principles of cause (as do many adults), and their unschooled rea- and effect. soning abilities may lead them to draw errone- â¢ foundations for modeling. ous conclusions. But young children are not the â¢ the ability to consider ideas and beliefs. bundles of misconceptions they are sometimes portrayed as being. They are active explorers â¢ an eagerness to participate in learning. who have successfully learned about regularities in particular domains of experience in ways that help them interpret, anticipate, and explain their worlds. Over time and with different experiences, childrenâs common sets of under- standing may diverge to some extent, and this diversity can be seen both within a 40 Ready, Set, SCIENCE!
single classroom and across cultures. Nevertheless, children continue to retain a shared base of understanding that can be a valuable foundation for the learning and teaching of science. Seeing Nature in New Ways Science education is sometimes seen as a straightforward process of filling students up with facts. According to this line of reasoning, if students learn enough con- cepts, definitions, and discrete facts, theyâll understand science. Learning new facts is important in science education. Young children wonât deepen their understanding of living things, for example, without learning about a variety of living things and their characteristics. But learning facts alone is not enough. To understand science, children also need to view facts in broader contexts of meaning. They need to reposition the ideas they bring with them to school within a larger network of ideas. They need to learn how to think about scientific explanations. Researchers group all of these kinds of changes in think- ing into the general category of conceptual change. The elementary and middle school years can include impressive periods of conceptual change. Children can have dramatic new insights that change the way they understand a whole domain. They can come to new understandings that lit- erally change their lives. Conceptual change of the kind that is needed in K-8 science instruction can be difficult to engineer. Many teachers have their students do experiments or make observations with the hope that scientific understanding will miracu- lously emerge from the data. Being exposed to new information, however, is not the same as understanding or integrating that information into what one already knows. Real conceptual change requires that deeper reorganizations of knowledge occur. Students who are proficient in science know more than mere facts. Their proficiency arises from the organization of their knowledge. Developing expertise in science means developing a rich, interconnected set of conceptsâa knowledge structureâthat comes closer and closer to resembling the structure of knowledge in a scientific discipline. When students understand the organizing principles of science, they can learn new and related material more effectively, and they are more likely to be able to apply their knowledge to new problems. Foundational Knowledge and Conceptual Change 41
Types of Conceptual Change There are several different types of conceptual change, some of which are more difficult to achieve than others. Many educators arenât aware of the different levels of difficulty, so they donât adjust their instruction when confronting differ- ent cases. It isnât always easy to know which kind of change is needed, and some change will require more time and effort on the part of both teachers and learners. Here we consider three broad types of conceptual change, beginning with the easi- est and progressing toward the most challenging. Elaborating on a Preexisting Concept The easiest kind of conceptual change involves elaborating on an already exist- ing conceptual structure. In biology, for example, students may learn how speciesâ anatomical features (e.g., teeth) convey information about the animalâs lifestyle (e.g., diet). Later they might investigate other body parts (e.g., claws, reproductive system) and extrapolate other behaviors (e.g., hunting, mating, cooperating). As students build a foundation of conceptual understanding, extending it with new evidence, knowledge, or experiences that fit well with their current thinking can be relatively easy to accomplish. Restructuring a Network of Concepts A more challenging type of conceptual change involves thinking about a preexist- ing set of concepts in new ways. Grasping the idea of air as matter, for example, requires a change in understanding of the concepts of both air and matter. Once this new understanding of air is fully integrated, the old idea that âair is nothingâ is no longer relevant and can be discarded. Restructuring a network of concepts can also involve uniting concepts previously thought to be fundamentally different or separate. For example, children may initially see liquids and solids as fundamentally different from air. Later they may come to see that all matter is made up of tiny particles and can exist in different âphases.â This requires a shift from thinking of matter as something that can be directly perceived (as something you can see, feel, or touch) to something that takes up space and has mass. Similarly, they must shift from seeing weight as something that is defined and assessed perceptually (how heavy something feels) to a magnitude that is measured and quantified. These steps are necessary if students eventually are to differentiate between weight and density. This type of conceptual change can be difficult and may require 42 Ready, Set, SCIENCE!
extensive and repeated opportunities to reexamine and think about the concepts in question. Achieving New Levels of Explanation Perhaps the most challenging type of conceptual change involves achieving new levels of explanation for particular phenomena; this type of conceptual change is necessary for the advance of studentsâ scientific understanding. To understand atomic-molecular theory, for example, they need to understand that materials con- sist of atoms and molecules, and they need to understand the behaviors and inter- actions of these microscopic constituents of matter. These new levels of under- standing provide for a much deeper understanding of many other phenomena, and they connect explanations in one area of science to explanations in other areas of science. For example, once students understand atomic- Types of Conceptual Change molecular theory, they are in a position to understand the basic biological processes of living things. 1. Elaborating on a preexisting concept Developing new levels of explanation can be chal- 2. Restructuring a network of concepts lenging because fundamental conceptual change requires that existing concepts be reorganized and placed within a 3. Achieving new levels of explanation larger explanatory structure. Learners have to break out of their familiar frame and reorganize a body of knowl- edge, often in ways that draw on unfamiliar ideas. Because of the complexity of this process, students are likely to require extensive and well-supported opportuni- ties to work on the development of these new levels of explanation. Using Prior Knowledge to Make Sense of the World One common approach to science education in the past has been to focus on studentsâ âmisconceptions.â Children often use their observations and common sense to arrive at conclusions about the world that are incomplete or incorrect. The extreme version of this view is that a kindergartner arrives at school with a bundle of mistaken ideas that need to be corrected. A more productive way to look at these misconceptions is to see them as childrenâs attempts to make sense of the world around them. It is true that science instruction should ultimately aim to have children understand scientific explana- tions of natural phenomena, but if one jumps to scientific explanations too fast, Foundational Knowledge and Conceptual Change 43
students will fail to master science in meaningful ways. Often their ideas are parts of larger systems of thought that make sense to them, even though they may be wholly or partially incorrect. Consider, for example, that many children (and adults) believe that tem- peratures in the summer are warmer than those in the winter due to the distance between the sun and earth. This is incorrect. Scientific accounts would point to the length of the day and the tilt of the earth as factors that account for seasonal tem- perature change. However, underneath the childâs reasoning is a way of thinking that works. The child knows, for example, that when she moves her hand closer to a radiator, it feels hotter. She can use this knowledge to navigate the world. The child who follows this kind of reasoning is linking her own experience with radia- tors and other hot objects, to the seasons, a new problem that she cannot experi- ence physically. She is essentially testing a âtheoryâ against a new observation. What we call misconceptions may be necessary stepping-stones on a path toward more accurate knowledge. They may coexist with some accurate ideas about the natural world. Mistaken ideas may be the only plausible way for a child to progress toward a more accurate understanding of scientific concepts. And not all errors necessarily require instructional intervention. For example, very young children often believe that individuals can become giants by eating heartily, that death can be reversed, or that if you break material into successively smaller pieces will make it disappear. While all of these views are obviously incorrect, they will generally self-correct without instruction as children go about their lives. Some aspects of modern scientific understanding are so counterintuitive and âunnaturalâ that a child is highly unlikely to arrive at that understanding without explicit instruction. Understanding atomic-molecular theory, for example, calls for children to imagine matter at a scale far removed from their everyday experi- ences. Their view that the kinds of materials in the world are infinitely varied is not easily reconciled with the notion that there are only about 100 different kinds of atoms on earth. While young children generally have many misconceptions about air, in the later years of elementary school they can begin to develop an initial macroscopic understanding of matter. They can begin to determine whether all material enti- ties have some properties in common and what those properties are. In this way, they can start articulating a general concept of matter that was initially implicit in their notions of kinds of materials. They can develop the idea that objects of dif- ferent materials are made of something that continues to exist, takes up space, and has weight across a broad range of transformations. 44 Ready, Set, SCIENCE!
Science Class MOLECULES IN MOTION2 The following case study involves a classroom of seventh graders struggling to understand a set of new and dif- ficult concepts. It focuses on a specific domain of scientific knowledgeâthe nature and properties of matter, including gases. At least some of this material will be unfamiliar to most educatorsâin fact, most adults struggle with the properties of gases and air pressure. Focusing on a specific example of teaching that incorporates all four strands demonstrates the power of using the strands together to engage kids in actively doing science. It also makes it possible to dig deeper into some of the new perspectives on conceptual understanding and scientific profi- ciency that offer so much potential for science education. Michelle Faulkner, a seventh-grade science teacher, were likely to think they knew what was happen- was beginning a unit on air, called âMolecules in ing in the demonstrations, because they would be Motion,â as an introduction to the atomic-molecular observing and working with everyday objects and theory of matter. situations familiar from their own lives. This famil- iarity and assumed knowledge would elicit a number of predictions and theories from them. Ms. Faulkner THE ATOMIC-MOLECULAR knew, however, that her students would quickly dis- THEORY OF MATTER cover that their usual explanations or assumptions did not, in fact, work well to explain what was going The atomic-molecular theory is a well- on. This, in turn, would encourage them to be more established body of scientific thought that open to exploring new tools and models and to helps make clear the properties of substances, developing new explanations. what things are made of, and how things The air pressure demonstrations were dramatic change (and do not change) under varied because, although air is invisible, air pressure pushes environmental conditions, such as heat in every direction with 14.7 pounds per square inch and pressure. The atomic-molecular theory at sea levelâa huge amount of force. Once stu- accounts for visible as well as invisible dents began to discover how air pressure works, Ms. (microscopic) aspects of substances. Faulkner hoped they would be motivated to greater exploration and mastery of other related scientific phenomena, such as the nature of molecular motion Ms. Faulkner had two reasons for starting with and the effects of heat. air pressure demonstrations at the outset of this Ms. Faulknerâs seventh graders loved to see unit. The first was that the textbook she used in chemical reactions, and the grander the better. class introduced the atomic-molecular theory with The problem with many of the demonstrations in dramatic air pressure demonstrations. Her second their science textbook was that they never really reason was that she knew these demonstrations understood the concepts behind the outcomes they would produce surprising and unexpected outcomes produced. They predicted what would happen, that would elicit studentsâ thinking about experi- invariably found the results surprising and interest- ences theyâve had with air pressure. The students ing, but due to time constraints were forced to move Foundational Knowledge and Conceptual Change 45
on too quickly to other demonstrations, memorizing âCool, itâs like the waterâs stuck in the glass.â At vocabulary, and completing worksheets. The dem- that moment, the rim of the glass broke the sur- onstrations also often overestimated the studentsâ face and the water flowed out in a rush. Everyone knowledge and experience, subtly communicating laughed. the message that, if only they were smarter, they âDo it again,â someone called. would be able to understand the outcomes better. âDo it with the taller glass,â Alliyah said, âand This time, Ms. Faulkner was determined to make see if that works.â sure that her students saw themselves as âdoing sci- âThatâs a great idea,â Ms. Faulkner said. She was ence,â not just seeing cool effects or memorizing thrilled that the kids were proposing their own ideas vocabulary for tests. for demonstrations, and she was happy to follow The day she began the new unit Ms. Faulkner their lead. She asked Alliyah to try the experiment arranged in front of the class an empty 10-gallon with the bigger glass, since it was her idea. aquarium, several different-sized drinking glasses, Alliyah placed the glass in the aquarium, turned and an empty glass milk bottle. She asked two it upside down, and filled it with water. As she students to fill the aquarium with water. Then she lifted the bottom of the glass slowly from the water added some blue food coloring so they could better in the tank, the water came see the contrast between the water and the air. with it (see Figure 3-2). Ms. Faulkner had chosen this particular dem- âCould we try it with onstration because she believed it made sense to an even taller glass?â asked start with something her students had probably Eriziah. âOr how about that seen before and could demonstrate to their parents graduated cylinder?â later at home. As her science students entered the âGo ahead and try it, FIGURE 3-2 classroom, she called for them to join her around a Eriziah,â said Ms. Faulkner. Large inverted glass central work area with the aquarium on a table in being lifted out of the As with the other two glass- the middle. water. es before, the water stayed âYouâve probably had this happen to you while in the graduated cylinder as Eriziah lifted it out of doing the dishes,â she said. âAnd itâs very strange.â the tank (see Figure 3-3). She chose a small drinking glass from the several she âSo whatâs going on here? Whatâs making the had gathered and put it into the aquarium, turning water stay in the glass?â Ms. Faulkner asked. No one it sideways so that all the air bubbled out. When the answered. Then Damian called out, âSuction! The glass was fully immersed in water gets sucked up into the glass like a vacuum!â the tank, she turned it upside âYou know what, Damien?â Ms. Faulkner down and slowly raised the responded. âA lot of adults would guess the same bottom, bringing the glass thing. They would say, âA vacuum sucks the water almost completely out of the up into the glass.â But Iâll tell you a saying that I water (see Figure 3-1). learned in my physics class in college: âScience never The students watched sucks!ââ The group erupted in laughter. as the water stayed in the Ms. Faulkner had expected that one of her stu- FIGURE 3-1 Small inverted glass being glass above the tank, as if dents would suggest suction or a vacuum as the cause. submerged in water. by magic. Someone said, This happened every time she taught students about 46 Ready, Set, SCIENCE!
it closely. One student sniffed it and said, âNothing.â Another said doubtfully, âAir?â âSo we have two different ideas on the table,â Ms. Faulkner said to the class. âWhat do the rest of you think?â Surprisingly, the students had a lot of different ideas about this. Some thought both ideas were pos- sible, because, as Jessa said, âair sort of is nothing, except if the wind is blowing.â As the students shared their ideas, Ms. FIGURE 3-3 Graduated cylinder being lifted out of the water. Faulkner recorded them on a large piece of chart paper. She titled the chart âWhat We THINK We air pressure. Suction as an explanation made sense to Know About Air,â reminding them that this was students because theyâd had actual experience with just the beginning of the investigation and their it. Drinking a milkshake through a straw, for instance, ideas were sure to change. She explained that it felt like âsuckingâ liquid into your mouth. was important for them to record their ideas now Ms. Faulkner wanted to give her students some so they could look critically at them later and see time to think about this explanation, rather than how they had changed over time, as more evidence simply telling them it was not valid. She also wanted was gathered. them to question their assumptions and move beyond Finally, Ms. Faulkner said, âLet me do one more the idea of suction just because it sounded scientific. demonstration that will add a little more data and She told them that they would explore the issue in help us think about air.â depth, amazing themselves and their parents by the The demonstration was designed to show the stu- end of the unit by knowing more about the physics of dents that air took up space even though it was invis- air pressure than most college graduates do. ible. Ms. Faulkner balled up a paper towel and stuck Then she briefly set out the plan of action. She it in the bottom of a large glass in such a way that it would do one more group demonstration. Then would stay there and not fall out when turned. She they would work at different stations around the turned the glass upside down so the opening was fac- room, called âsituation stations,â in groups of four, ing the water in the tank (see Figure 3-4). exploring different activities with air and water. âIâm going to push the They would have a short amount of time to rotate glass down into the water. through all of the different stations, after which What do you think will they would choose one station to focus on. Each happen? Will the paper group would put together a report for the rest of get wet?â the class, trying to explain what was going on at Everyone wanted to their particular station. talk at once. Ms. Faulkner After explaining the plan of action, Ms. Faulkner told each student to turn FIGURE 3-4 took the top off a clean mayonnaise jar and passed to the person next to Partially submerged the jar around, asking the students to tell her what upside-down glass with them and discuss their balled-up paper towel. was in it. They turned it upside down, examining ideas. The room filled Will the paper get wet? Foundational Knowledge and Conceptual Change 47
with talk as the students discussed with their partners Most of the students voted for Prediction 1, sev- the experiment they were about to try. Ms. Faulkner eral for Prediction 2, and a few for Predictions 3 and 4. Then Ms. Faulkner asked the students to explain the reasons for their predictions, telling them they were free to change their minds at any point if they heard something that convinced them to rethink their position. April went first because she and her partner had proposed Prediction 1. âAt first we thought the water would just go into the glass, because, you know, it seems like thereâs nothing in there,â April said. âBut then I heard someone else saying theyâd done it and no water went in, and I changed my mind. I guess, like Joanna said, thereâs air in the glass and the air wonât let the water in.â Phuong spoke next. She was from Vietnam and had lived in the United States for only two years, but circulated around the room and listened in on differ- she was fascinated by science. ent conversations, noting a range of predictions. âI say 4. I donât think the water will go in After a few minutes, she brought the studentsâ because air is everywhere in the glass but not where attention back to the front of the room and asked the paper is.â different partners to share their predictions, which Ms. Faulkner said, âSo are you agreeing with she wrote on the whiteboard. There were four dif- April? Youâre both saying no water at all will go ferent predictions: in the glass and the paper will be dry?â Both girls nodded. 1. The glass will be filled with water and the paper Phuong continued, âI know air is real. It takes will get wet. up space and keeps water away from the paper.â 2. A lot of water will go in the glass but the paper Ms. Faulkner asked for someone who had voted will not get wet. for Prediction 3âpredicting that a little water would go into the glassâto explain their reasoning. 3. A little water will go in the glass but the paper Joanna volunteered. will not get wet. âWell, actually, I think this is probably wrong, but me and Tanika were thinking that water is 4. No water will go in the glass and the paper will heavier and has more force than air, and it might not get wet. force the air into a smaller and smaller space, Ms. Faulkner asked the students to vote, by a show and even squish up the paper. But we agree with of hands, for the prediction they agreed with. She Juanita and April. Weâre pretty sure the paper explained that the voting was intended not as a basis wonât get wet.â for determining correctness but to let everyone get a Finally Ms. Faulkner did the demonstration. The sense of each otherâs views of the most likely outcome. students watched, craning their necks and getting 48 Ready, Set, SCIENCE!
out of their seats to see the said Ms. Faulkner. âLet me see if I understand what aquarium, as she pressed the youâre saying. Are you saying that the air is getting upside-down glass slowly into the pressed up by the water, or compressed?â water (see Figure 3-5). Tanika nodded. âItâs like the air is getting It was difficult to see what was squished.â happening because everything Ms. Faulkner added the words âair is squishable looked blue. One of the students or compressibleâ to the âWhat We THINK We Knowâ pointed out that the paper wasnât chart. getting wet, and the water went âAre there any other things we think we know only a little way up into the glass. FIGURE 3-5 about air? Turn to the person sitting next to you Someone else noticed that the Fully submerged and talk for a minute about both of the demos glass: only a small farther down into the water the weâve done. I want you to think about anything you amount of water glass was pushed, the more water gets in. think you know about air. And talk about what the went into it. bases for your claims about air are and how certain Ms. Faulkner pulled the glass out of the water, you are about your ideas.â took out the paper, and showed it to everyone. Ms. Faulkner circulated among the students. It was completely dry! To prove it, she passed the Everyone seemed to be talking, even students who paper around to each student. were usually reluctant to speak in a large group. âSo what have we figured out with this experi- After calling the group back into session, she ment?â Ms. Faulkner asked. âWhich prediction fits decided to start with Jorge and Salizar, who felt cer- the results the best, and why didnât the paper get tain that air was everywhere. Sheâd overheard them wet? Go back to your seats and letâs talk about this.â speaking both in English and Spanish, and sheâd As soon as he sat down, Jeremy waved his hand heard the word molÃ©culas. She called on Jorge, the excitedly. Ms. Faulkner waited patiently for more quieter of the two, to explain what he and his part- hands to go up. After about 10 seconds she called ner had come up with. Ms. Faulkner stood poised to on Tanika, who didnât typically volunteer to speak. write on the âWhat We THINK We Knowâ chart, and âI think what we figured out is that the glass she reminded them again that these were just âfirst has air in it and that the air keeps the water out,â draftâ ideas, as she called them, that would probably said Tanika. âEven though you canât see it, itâs there. change a lot over the course of the unit. And the reason the water went in a little, is like Jorge spoke first. âMe and Salizar, we think air is what Joanna and I were saying, that the water is everywhere. PequeÃ±itos, molÃ©culas.â maybe stronger than the air and kind of forces it âI read in a book that molecules are really, really into a smaller space.â small, too small to see without a microscope,â Salizar âCan you say more about that?â asked Ms. said. Faulkner. Ms. Faulkner wrote, âAir is everywhere, made up âMaybe itâs like forcing a suitcase closed. You of tiny molecules.â press all the clothes down and even though itâs the Other students shared their ideas. Joanna spoke same amount of clothes, they take up less space.â for herself and Sherrie. âThatâs a really interesting way of thinking about âWell, we sort of agree and sort of disagree. the same amount of stuff taking up less space,â We donât think thereâs air in space. Maybe thereâs Foundational Knowledge and Conceptual Change 49
air everywhere on earth, but not really everywhere. Over the next several days, each of the groups Weâre not completely sure if thereâs air on the attempted to explain what was happening at their moon, but weâre pretty sure thereâs no air in space. specific station. Each group developed a poster Thatâs why astronauts have to wear spacesuits.â that showed the demonstration in action and Everyone laughed. Ms. Faulkner said, âDo you want me to change our âWhat We THINK We Knowâ chart?â Jorge suggested adding âon earthâ to âair is everywhere.â Shanita went next. âAir is a gas, right? Not a liquid or a solid. The molecules are moving around really, really fast. We learned this in sixth grade, but I canât remember the difference between molecules and atoms.â Ms. Faulkner recorded these ideas, with question marks next to âmoonâ and âatoms.â She felt the class had made a great start. She directed them to a much tried to explain what was pushing what. Groups smaller wall chart, which showed their eight assigned presented to the class, and the students in the groups and the stations theyâd specialize in. Around audience responded with questions, challenges, the room were four very different set-ups, each involv- comments, and suggestions based on what they ing air and water, making use of soda bottles, cups had discovered at their own stations. Ms. Faulkner and paper, straws, and large and small graduated cyl- made sure that the discussion stayed focused on inders. She told her students they would have 5 min- what was pushing what, in what direction, and on utes to spend at each of the four different stations. what was causing change to occur. They would then have 15 additional minutes to spend After the last group presented, Ms. Faulkner at the station they would specialize in, and they would told the students she wanted to try to consolidate continue the next day as well. Because there were their findings. The âWhat We THINK We Knowâ two different versions of each station, each of the chart was now full of new notes that the students eight groups had its own set-up to explore in depth. had added on their own, such as âair pushes up For the next 20 minutes, the students moved and down and sideways,â âair has more force than from station to station in 5-minute blocks, reluctant water,â and âair is squishable and can be made to leave each station when Ms. Faulknerâs timer smaller.â There were still, not surprisingly, several rang. When it was time to specialize, the students explanations that used the notion of a vacuum or settled around their designated stations and began suction. working. They took notes and drew pictures in their Ms. Faulkner told the class that she was going to lab notebooks, talking excitedly. start a chart called âWall of Accepted Scientific Facts.â After 15 minutes, the bell rang. The students âThese are ideas about air that are currently were so engrossed in their stations they didnât want accepted as fact by the scientific community,â she to stop. Ms. Faulkner was pleased and told them said. She pointed out that some of the facts were theyâd have more time the next day. the same as the ideas the students themselves had 50 Ready, Set, SCIENCE!
come up with, while others had taken scientists hit a wall, bounce off, and by chance, they bop out hundreds of years to figure out. Some ideas, she the door.â She wrote on the âAccepted Factsâ chart: explained, might be hard for them to believe. âIâm going to put up these facts, and weâre â¢ Air molecules are constantly moving, but without intention or knowledge. going to see if we understand and accept them or if we still have questions.â She told the class that â¢ Air molecules are moving very fast in every direc- 100 years ago a wall of facts about air would have tion, and they donât stick to one another, so they looked different, and it might look a bit different canât pull; they only push. 100 years from now. âWe still might want to add to these, or rephrase them a bit as we continue our Then Ms. Faulkner added some more âsurpris- unit, but these have a different status than the ideas ing facts,â as she called them. She told the kids in our âWhat We THINK We Knowâ chart.â that scientists often say we live at the bottom of an Of the facts she put on the âAccepted Factsâ chart ocean of air. âScientists think of both air and water was one theyâd already proposedâthat air was all as fluids. Fluids push in every directionâup, down, around them, even though they couldnât see it. She and sidewaysâjust like you saw in your stations. confirmed that it was made up of tiny, tiny particlesâ And with both air and water, thereâs more push, air moleculesâso small they couldnât be seen with a more force, the deeper down you go. Remember regular microscope. As Shanita had said, air molecules when you found that it got harder and harder to are constantly moving, very fast, in every direction. push the drinking glass into the aquarium?â The Ms. Faulkner demonstrated this fact, pointing up students nodded. under her chin, pressing on the outside of her nose, Shanita said, âOh yeah, and remember how even on the inside of her nostril. She explained we pushed an empty, upside-down glass into the that the air was pressing equally everywhere, on aquarium and the further down we pushed it, the the front and back of her ear lobe and on the out- more the air got squished, or um, compressed? It side of their noses as well as the inside. âOtherwise seemed like the water had more force the deeper your nostrils would collapse (she pressed her nostrils in the tank we went.â closed) and you wouldnât be able to breathe! So âThatâs another demonstration of the way that thereâs just as much air pressure on the inside of the pressure in a fluid is greater the deeper down your nostril as on the outside. If something is not you go,â Ms. Faulkner said. âAnd air is also a fluid. moving, it doesnât mean that thereâs no air pressure. The air molecules at the bottom of the âocean of airâ It means the forces of the air are balancedâpushing are more squished together, or compressed, at sea equally in all directions. So air molecules are bounc- level because of the weight of all the air molecules ing every which wayâdown, sideways, upâon every above them. In fact, at sea level, thereâs 14.7 pounds square inch of my body. But hereâs something really of air pushing on every square inch of your body! important. Scientists donât say that the air molecules Who can think of something that weighs that much, want to move or decide to move. They just move. almost 15 pounds?â They donât want or try or desire to move. Thereâs Eriziah said, âI have a 15-pound dumbbell at no intention or knowledge. Itâs not like they know home, and man that thing is heavy!â âMaybe thereâs a door open and decide to go out the door. two gallon jugs of water one on top of another?â Instead, they get pushed by another molecule and Shanita volunteered. Foundational Knowledge and Conceptual Change 51
âYes, but Iâm talking about 14.7 pounds per âIâm getting it, I think,â said Damian. âThe square inch, donât forget,â said Ms. Faulkner. An water is pushed into the glass by the air pressing adult man has about 100,000 pounds of air, pushing down on the surface of the water in the aquarium? in every direction, on his body, up, down, sideways.â Itâs like the air is forcing or squirting the water up She drew a square inch on her arm in blue magic into the glass. Like if you slap your hand down on marker. âThereâs 14.7 pounds, almost 15 pounds, of water, it sort of splashes up?â air pressing down right here.â âCan anyone remember how much pressure âHow come we canât feel it?â Eriziah asked. there is, how much force there is on every square âGreat question.â Ms. Faulkner said. âWe canât inch of the water in the fish tank?â feel it because weâre used to it. Our bodiesâand every Jorge looked up at the wall of facts and said, â14.7 living thing on earthâhave evolved to live under these pounds per square inch of air pressing on the water.â conditions. So itâs normal for us. But the change in Then Ms. Faulkner gave them an example, which air pressure is why your ears pop when you hike up she sketched on the board (replicated in Figure 3-6). a mountain or fly in a plane. If you took an inflated If instead of using a regular glass, upside down, to balloon that you blew up here, where weâre close to pull out of the aquarium, they used a glass that had a sea level, and carried it all the way to Denver, which one-square-inch opening, like a rectangular bud vase, is a mile above sea level, the balloon would be larger the water in the vase would weigh however much a in Denver because thereâd be fewer air molecules hit- column of water one inch by one inch weighs. That ting the balloon on the outside, so there would be less depends, of course, on the height of the column of resistance against the molecules inside the balloon.â water, because the more water in the column, the A few of the students were beginning to think more it would weigh. Still, there was no way that about the first demonstration again, which many the water in a column of 5 inches would weigh 14.7 still explained as having to do with suction. pounds. As a result, the air pressure on the surface of âWait a second,â Damian said. âYouâre saying the the water would keep the water in the glass. water is pushed into the glass, not sucked in?â Ms. Faulknerâs diagram looked something like this: Ms. Faulkner asked if anyone could put into Phuong asked a question that Ms. Faulkner wasnât their own words what Damian had said. Eriziah anticipating. âHow much would the water weigh wanted to try. in that bud vase if it was like 5 inches high?â Ms. âDamian said the air wasnât sucked into the glass like with a vacuum, like he first thought it was.â weight of column of water in 1-inch-square bud vase Ms. Faulkner nodded. âBut why canât the water 14.7 pounds per square get sucked into the glass? Why canât the air in the inch of air pressure glass suck up the water?â Ms. Faulkner used her trick of silently counting to 10 before speaking, in order to give her students time to think. Finally, Tanika raised her hand. âIs it because the air molecules are moving so fast, like it says on the wall of facts, they canât pull, they can only push?â She FIGURE 3-6 paused. âSo air canât pull or suck? It can only push?â Ms. Faulknerâs diagram of air pressure. 52 Ready, Set, SCIENCE!
Faulkner decided she would follow Phuongâs lead and take a minute to figure it out and then talk to the take a bit of a detour to explore her question. She person sitting next to you.â sensed that figuring out the weight of a column of There was silence for a few moments as students water that was one inch by one inch might help her worked alone, and then partner talk took off. Two students, down the road, in thinking about pressure students showed their workâdrawing 5 cubic inches more generally as a ratio of force per area. on top of one another and multiplying Phuongâs She asked the students to propose ways they could results of 0.036 pounds per cubic inch by 5 inches, investigate the answer to Phuongâs question. Again with the answer of 0.18 pounds of water. There was she wrote proposals, figuring someone might come up uniform agreement that this was how much the 5- with a solution that the class could work on as home- inch column of water would weigh. work. A number of suggestions were proposed: Jason asked if there would be more force push- ing the water into the glass in a larger aquarium Get a hollow one-cubic-inch container and weigh because there would be more total pounds of air on it before and after you fill it with water and sub- the surface of the water. âOr what if it was like a tract the weight of the container. Then multiply huge swimming pool full of water?â that by 5, for the 5-inch height. âJason has asked a really important question,â Measure the aquarium carefully to find out how Ms. Faulkner said. âHe asked if there would be many cubic inches it holds, and then weigh it more air pressure pushing down on the water in a both empty and filled with water. Then subtract bigger tank, or a swimming pool, or an ocean? The the container and divide the total by the number answer that the science community would give is of cubic inches. Multiply that by 5. that the pressure would be the same on every square inch, so the amount of water doesnât matter. Itâs Ask a scientist! the weight of the air per unit area.â She reminded them that pressure is always a ratio, a relationship Get a syringe and fill it with the number of milli- between two thingsâforce per area. liters of water that would equal a cubic inch of The concept of a ratio, Ms. Faulkner knew, was water and weigh the syringe with and without an important one in science, and the class had spent water. a great deal of time learning about ratios and using Finally, much to Ms. Faulknerâs surprise, Salizar different analogies to understand them. called out, âJust Google it!â He walked over to the This time, Ms. Faulkner used an analogy that computer and âGoogledâ weight of cubic inch of related directly to pressure. She asked her students water and less than 5 seconds later said, âIâve got it! to imagine all of the girls in the class walking across Water weighs 0.036 pounds per cubic inch or 8.33 a lawn in high heels versus flat-soled running shoes. pounds per gallon.â Ms. Faulkner wrote down the Everyone could imagine right away that the girls results. Shanita added, âThatâs way less than the would make a deeper indentation in the dirt if they 14.7 pounds per square inch that the air is pressing were walking in high heels. down with.â âYou weigh the same, but the pressure on the Ms. Faulkner directed the students back to high heel is pressing on a much smaller area. Pressure Phuongâs original question. âHow much would the is a ratio: how much force there is in relationship water in this 5-inch-high bud vase weigh? Everyone to how much area there is.â Then Ms. Faulkner Foundational Knowledge and Conceptual Change 53
brought them back to the situation in the aquarium. inch, thereâs no air, no nothing, I mean no pressure âSo even if the surface area of the water is huge, pushing the water down. So the water would squirt what matters is how many and with how much force up through the hole! If we had the one-inch glass the air molecules pound each square inch of the there, the bud vase thingy, then the water would surface of the water. Wherever you are, at sea level squirt up into it. When the water column goes or in the mountains, you donât have to calculate higher and higher it gets heavier and heavier, and the surface area in a container, or in a swimming at some point, eventually, the water will weigh as pool, or in a huge lake, because at the same eleva- muchâdownâas the air is pushing up. Thatâs as tion, every single square inch has exactly the same far as it could go.â After a long pause he said, âSo amount of air pressure on it.â how many of Salizarâs little cubic inches could we After a moment, Monica asked, âHow tall a glass pile up on top of one another? How many would could we pull out of the aquarium? How far could equal up to 14.7 pounds?â the column of water be pushed up, by air?â âPhuongâs on the right track when she asks âCould it go all the way up into space?â some- how many of Salizarâs little cubic inches could we one else asked. pile up on top of one another to equal the air pres- Salizar quickly responded, âIt couldnât go that far sure at 14.7 pounds per square inch,â Ms. Faulkner up because thereâs only 14.7 pounds per square inch said. âItâs really a question of balancing forces. Itâs pushing down. If the water weighed more than 14.7 like a seesaw. Weâve got someone on one side who pounds per square inch, it wouldnât stay up. The weighs 14.7 pounds. Thatâs the air pressure. On the water would win in the battle of the forces!â other side, weâve got a one-inch-square column of âSo how far can the air push the water up?â water. With what weâve figured out already, see if Monica asked again. you can figure out how tall that column of water âI donât know the answer to that question,â Ms. could be. And, even more interesting, see if you can Faulkner admitted. âBut Iâm sure we can figure it figure out a way we could test it to see if our calcu- out. Any ideas about how to get started? What lations are right. Think about it tonight, and weâll would we need to know?â talk about it tomorrow.â There was silence. Finally, Tanika said, âHow By the next day, the class had calculated that many cubic inches of water does it take . . . um, the air could hold up a column of water 34 feet tall. to weigh more than the air pressureâlike 14.7 They had come up with many different methods, pounds?â but the simplest was building on Salizarâs fact that As if finishing Tanikaâs sentence, Monica con- a cubic inch of water weighs 0.036 pounds. They tinued, âLike how many cubic inches of water can divided 14.7 pounds by 0.036 pounds (per cubic inch) push down on that spot to outweigh the air pressure and came up with 408.3 cubic inches. Thatâs how thatâs forcing the water up?â many cubic inches of water could be piled on top of Phuong said, âI think I get it. Itâs like the air each other to equal 14.7 pounds. They then divided pressure is pressing down on the surface of the that by 12 to determine the feet and got 34.03 feet. aquarium, everywhere, like a piece of plywood Ms. Faulkner applauded her studentsâ hard work pressing down with a lot of force, like a lot of force. and amazing resultsâthey had truly changed their And then we cut a hole in the plywood, like a one- conceptual thinking in many ways. square-inch hole. And right there, on that square 54 Ready, Set, SCIENCE!
Examining Conceptual Change in Molecules in Motion In the âMolecules in Motionâ unit, students began with many ideas about air based on their personal experience. For example, some students began the unit thinking that air was nothing, except when you could feel it as wind. For most of the students, the investigations with air pressure entailed building on their preex- isting concepts of air and elaborating on themâthe first type of conceptual change described earlier in this chapter. After eliciting ideas from the students for the âWhat We THINK We Know About Airâ chart, Ms. Faulkner introduced some new facts about air mol- ecules. The students grappled with these facts as they attempted to understand and explain why water stayed in a glass as it was pulled, upside down, out of an aquarium full of water. After the first group discussion and demonstration, all of the students were certain that air was somethingâsomething that took up space in an âemptyâ glass. âSomethingâ is a concept that the students entered with and that they elaborated on to include air once they were persuaded that air qualified as something. This was an important development for their continued learning and understanding of matter. Helping students elaborate the concept that air is something took only a modest instructional intervention. At this point, the students were beginning to rethink and restructure the net- work of existing concepts about air, molecules, forces, and pressureâthe second type of conceptual change we discussed above. Many questions, conjectures, and divergent ideas were made public. Over several days of investigation and discus- sion, students learned to embrace and apply the notion that air pressure pushed the water up into the glass, and that asymmetrical levels of air pressure within a system would predictably result in such movement. This entailed developments in their thinking about air, the way it pushes in all directions, and the magnitude of force with which it pushes. Ultimately, the students would go on to build new levels of explanation, the third type of conceptual change, either in Ms. Faulknerâs class or in subsequent grades. That is, they will come to understand atomic-molecular theory and use it to explain phenomena like air pressure. The students will also learn to under- stand increasingly more complex material explanations. Once they master macro- scopic explanations, they will go deeper into atomic-molecular theory and develop an explanation of phase change and motion at the molecular level. They will learn that molecular theory is a basic and broadly applied idea that can help them Foundational Knowledge and Conceptual Change 55
make sense of processes in other domains. The foundation built in Ms. Faulknerâs classroom will be critical for their success in subsequent years. What specific classroom activities and forms of instruction supported the studentsâ conceptual reorganization? First, itâs important to note that Ms. Faulkner began the unit by recognizing and honoring studentsâ everyday knowl- edge in order to transform and build on it. She convinced her students that air is matter and takes up space, not by telling them but by letting them observe the empty glass being pushed into the water while not letting any water in. They could not see the air, but they could see its force on the water. They could also see that air is compressible or, as they described it, âsquish- able.â They saw that the water entered the glass a little bitâevidence that the water was forcing the air into a smaller space. They couldnât see molecules, but the idea of air pressure allowed them to make sense of the idea of air getting squished into a smaller space. In their situation stations, the students experienced multiple demonstrations and activities that helped them exploreâand revisit in new formsâsome of the ways in which air and water act. These experiences provided them with specific and shared experiences to integrate, think with, and generalize from. The demonstrations were designed to enable the students to recognize evi- dence that air presses up, down, and sideways and has fluid-like properties. They experienced the phenomenon of differential pressure in a gravitational fieldâthe deeper down, the more pressureâin a column of air or water. These demonstra- tions also provided students with opportunities to work with and clarify their ideas. Working in small groups gave everyone time to try out their own ideas and hear the ideas of their teammates. This helped them prepare a presentation about their particular demonstration to share with the rest of the class. Work at the stations gave the students time to manipulate the materials, think about their counterintuitive outcomes, and prepare to present their ideas to others. Time for thinking, doing, and talking is essential for understanding complex ideas, espe- cially ideas that require a transformation in oneâs everyday thinking. Building Understanding Over Multiple Years Of course, the capabilities of young children along each of the four strands are also limited in important ways. They have only limited understanding of dif- ferent materials, of physical quantities such as weight or volume, and of how to 56 Ready, Set, SCIENCE!
construct knowledge in science. They might know something about the objects they encounter in their everyday lives, but their experience with other materials or the transformation of materials is still limited. For example, they may deny that an object broken into tiny pieces is still the same kind of stuff because it no longer âlooks likeâ the same stuff. Many of the most enduring and essential characteristics of materials (such as density, boiling and melting points, thermal and electrical conductivity, and solubility) are unknown to them. Also, young childrenâs understanding of the material world is based on their perceptual experiencesâon what they can see, feel, or touch. For example, they think of weight as something that they can feel with their hand. They may think, for example, that a piece of Styrofoam weighs ânothing at allâ because it seems to exert no force on their hand. They rely on how heavy something feels because they have not yet differentiated weight and density. While children may have amazing skills and capabilities to learn science, people do not spontaneously generate scientific understanding. The develop- ment of early ideas about matter, in which neither mass nor volume is considered a defining property, into a sophisticated understanding of atomic theory clearly requires formal academic instruction. Nor do people spontaneously generate deep scientific understanding of other core domains. The theory of evolution, for example, although fundamental to modern science, can be quite difficult to under- stand. Many children and adults embrace erroneous beliefs about evolution. The complexities of science and science learning are real. To acknowledge this is to also concede that good science teaching requires extensive teacher knowl- edge, excellent curriculum, effective systems of support and assessment, and much more time and attention than are currently devoted to it. This can be daunting. While the complexity of science poses significant instructional challenges, the interrelatedness of science makes it possible to focus and simplify curriculum and instruction in another important way. Science can be organized instruction around a small number of concepts. These âcore conceptsâ have great explanatory power and can be built on in increasingly complex ways from year to year. In the next chapter, weâll see how this process can work, not only for atomic-molecular theory but also throughout the disciplines of science. Foundational Knowledge and Conceptual Change 57
For Further Reading Baillargeon, R. (2004). How do infants learn about the physical world? Current Directions in Psychological Science, 3, 133-140. diSessa, A., and Minstrell, J. (1998). Cultivating conceptual change with benchmark les- sons. In J. Greeno and S. Goldman (Eds.), Thinking practices (pp. 155-187). Hillsdale, NJ: Lawrence Erlbaum Associates. Inagaki, K., and Hatano, G. (2002). Young childrenâs naÃ¯ve thinking about the biological world. New York: Psychology Press. Kuhn, D. (2002). What is scientific thinking and how does it develop? In U. Goswami (Ed.), Blackwell handbook of childhood cognitive development (pp. 371-393). Oxford, England: Blackwell. Kuhn, D., and Franklin, S. (2006). The second decade: What develops (and how)? In W. Damon and R. Lerner (Eds.), Handbook of child psychology (6th ed.). New York: Wiley. Lehrer, R., and Schauble, L. (2002). Symbolic communication in mathematics and science: Co-constituting inscription and thought. In E.D. Amsel and J. Byrnes (Eds.), Language, literacy, and cognitive development: The development and consequences of symbolic communication (pp. 167-192). Mahwah, NJ: Lawrence Erlbaum Associates. Metz, K.E. (1995). Reassessment of developmental constraints on childrenâs science instruc- tion. Review of Educational Research, 65, 93-127. Metz, K.E. (2004). Childrenâs understanding of scientific inquiry: Their conceptualization of uncertainty in investigations of their own design. Cognition and Instruction, 22(2), 219-290. National Research Council. (2007). Foundations for science learning in young children. Chapter 3 in Committee on Science Learning, Kindergarten Through Eighth Grade, Taking science to school: Learning and teaching science in grades K-8 (pp. 53-92). R.A. Duschl, H.A. Schweingruber, and A.W. Shouse (Eds.). Center for Education, Division of Behavioral and Social Sciences and Education. Washington, DC: The National Academies Press. 58 Ready, Set, SCIENCE!