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Ready, Set, SCIENCE!: Putting Research to Work in K-8 Science Classrooms
220 pages | 8.25 x 10 | HARDBACK ISBN 978-0-309-38633-3 | DOI 10.17226/11882
Sarah Michaels, Andrew W. Shouse, and Heidi A. Schweingruber; Board on Science Education; Center for Education; Division of Behavioral and Social Sciences and Education; National Research Council
Ready, Set, SCIENCE!: Putting Research to Work in K-8 Science Classrooms
Copyright National Academy of Sciences. All rights reserved.
37
3Foundational Knowledge and Conceptual Change Recent research has revolutionized views of how children’s 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 “theories,”1 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:
• How does one recognize the knowledge that children bring to school?
• How does one build on this knowledge in ways that specifically support science learning?
• How does one make diversity (in culture, language, or prior experience) a resource rather than an obstacle?
• 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
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Ready, Set, SCIENCE!38
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 students’ 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 “domains.” 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 (naïve physics), behaviors of psychological agents (naïve psychology), actions and organization of living things (naïve biology), and makeup and substance of materials (naïve 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 “fit” biological niches that serve their survival needs. These are just a few examples of the fairly broad basic under- standing that young children derive from their experience in the world even before formal instruction begins.
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
1. Simple mechanics of solid bounded objects
2. Behaviors of psychological agents
3. Actions and organization of living things
4. Makeup and substance of materials
Four Domains of Knowledge
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Foundational Knowledge and Conceptual Change 39
specific. For example, in physics, children observing a rolling ball understand that the ball has no “desire” to roll down a ramp and that when it hits a wall it doesn’t “want” 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, don’t 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 child’s 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
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original identity, character, or function. Later in school, they build on similar under- standing to use counters to solve simple early arithmetic problems.
Young children’s 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 modeling—a fun- damental aspect of contemporary scientific practice—even before kindergarten.
In addition, children are able to understand their own and others’ 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 ideas. They discuss ideas and debate positions with a sophistication that is often surprising.
Even very young children can engage in all four strands of scientific proficiency. They typi- cally have significant gaps in their understanding (as do many adults), and their unschooled rea- soning abilities may lead them to draw errone- ous conclusions. But young children are not the bundles of misconceptions they are sometimes portrayed as being. They are active explorers 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, children’s common sets of under-
standing may diverge to some extent, and this diversity can be seen both within a
• rich knowledge of the natural world.
• the ability to reason.
• an understanding of the principles of cause and effect.
• foundations for modeling.
• the ability to consider ideas and beliefs.
• an eagerness to participate in learning.
Young children begin school with…
Ready, Set, SCIENCE!: Putting Research to Work in K-8 Science Classrooms
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Foundational Knowledge and Conceptual Change 41
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, they’ll understand science.
Learning new facts is important in science education. Young children won’t 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 concepts—a knowledge structure—that 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.
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Types of Conceptual Change
There are several different types of conceptual change, some of which are more difficult to achieve than others. Many educators aren’t aware of the different levels of difficulty, so they don’t adjust their instruction when confronting differ- ent cases. It isn’t 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 species’ anatomical features (e.g., teeth) convey information about the animal’s 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 “air is nothing” 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 “phases.” 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
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Foundational Knowledge and Conceptual Change 43
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 students’ 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- molecular theory, they are in a position to understand the basic biological processes of living things.
Developing new levels of explanation can be chal- lenging because fundamental conceptual change requires that existing concepts be reorganized and placed within a 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 students’ “misconceptions.” 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 children’s 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,
1. Elaborating on a preexisting concept
2. Restructuring a network of concepts
3. Achieving new levels of explanation
Types of Conceptual Change
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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 child’s 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 “theory” 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 “unnatural” 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.
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Foundational Knowledge and Conceptual Change 45
Science Class
Michelle Faulkner, a seventh-grade science teacher,
was beginning a unit on air, called “Molecules in
Motion,” as an introduction to the atomic-molecular
theory of matter.
Ms. Faulkner had two reasons for starting with
air pressure demonstrations at the outset of this
unit. The first was that the textbook she used in
class introduced the atomic-molecular theory with
dramatic air pressure demonstrations. Her second
reason was that she knew these demonstrations
would produce surprising and unexpected outcomes
that would elicit students’ thinking about experi-
ences they’ve had with air pressure. The students
were likely to think they knew what was happen-
ing in the demonstrations, because they would be
observing and working with everyday objects and
situations familiar from their own lives. This famil-
iarity and assumed knowledge would elicit a number
of predictions and theories from them. Ms. Faulkner
knew, however, that her students would quickly dis-
cover that their usual explanations or assumptions
did not, in fact, work well to explain what was going
on. This, in turn, would encourage them to be more
open to exploring new tools and models and to
developing new explanations.
The air pressure demonstrations were dramatic
because, although air is invisible, air pressure pushes
in every direction with 14.7 pounds per square inch
at sea level—a huge amount of force. Once stu-
dents began to discover how air pressure works, Ms.
Faulkner hoped they would be motivated to greater
exploration and mastery of other related scientific
phenomena, such as the nature of molecular motion
and the effects of heat.
Ms. Faulkner’s seventh graders loved to see
chemical reactions, and the grander the better.
The problem with many of the demonstrations in
their science textbook was that they never really
understood the concepts behind the outcomes they
produced. They predicted what would happen,
invariably found the results surprising and interest-
ing, but due to time constraints were forced to move
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 knowledge—the nature and properties of matter,
including gases. At least some of this material will be unfamiliar to most educators—in 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.
THE ATOMIC-MOLECULAR THEORY OF MATTER
The atomic-molecular theory is a well- established body of scientific thought that helps make clear the properties of substances, what things are made of, and how things change (and do not change) under varied environmental conditions, such as heat and pressure. The atomic-molecular theory accounts for visible as well as invisible (microscopic) aspects of substances.
Ready, Set, SCIENCE!: Putting Research to Work in K-8 Science Classrooms
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on too quickly to other demonstrations, memorizing
vocabulary, and completing worksheets. The dem-
onstrations also often overestimated the students’
knowledge and experience, subtly communicating
the message that, if only they were smarter, they
would be able to understand the outcomes better.
This time, Ms. Faulkner was determined to make
sure that her students saw themselves as “doing sci-
ence,” not just seeing cool effects or memorizing
vocabulary for tests.
The day she began the new unit Ms. Faulkner
arranged in front of the class an empty 10-gallon
aquarium, several different-sized drinking glasses,
and an empty glass milk bottle. She asked two
students to fill the aquarium with water. Then she
added some blue food coloring so they could better
see the contrast between the water and the air.
Ms. Faulkner had chosen this particular dem-
onstration because she believed it made sense to
start with something her students had probably
seen before and could demonstrate to their parents
later at home. As her science students entered the
classroom, she called for them to join her around a
central work area with the aquarium on a table in
the middle.
“You’ve probably had this happen to you while
doing the dishes,” she said. “And it’s very strange.”
She chose a small drinking glass from the several she
had gathered and put it into the aquarium, turning
it sideways so that all the air bubbled out. When the
glass was fully immersed in
the tank, she turned it upside
down and slowly raised the
bottom, bringing the glass
almost completely out of the
water (see Figure 3-1).
The students watched
as the water stayed in the
glass above the tank, as if
by magic. Someone said,
“Cool, it’s like the water’s stuck in the glass.” At
that moment, the rim of the glass broke the sur-
face and the water flowed out in a rush. Everyone
laughed.
“Do it again,” someone called.
“Do it with the taller glass,” Alliyah said, “and
see if that works.”
“That’s a great idea,” Ms. Faulkner said. She was
thrilled that the kids were proposing their own ideas
for demonstrations, and she was happy to follow
their lead. She asked Alliyah to try the experiment
with the bigger glass, since it was her idea.
Alliyah placed the glass in the aquarium, turned
it upside down, and filled it with water. As she
lifted the bottom of the glass slowly from the water
in the tank, the water came
with it (see Figure 3-2).
“Could we try it with
an even taller glass?” asked
Eriziah. “Or how about that
graduated cylinder?”
“Go ahead and try it,
Eriziah,” said Ms. Faulkner.
As with the other two glass-
es before, the water stayed
in the graduated cylinder as Eriziah lifted it out of
the tank (see Figure 3-3).
“So what’s going on here? What’s making the
water stay in the glass?” Ms. Faulkner asked. No one
answered. Then Damian called out, “Suction! The
water gets sucked up into the glass like a vacuum!”
“You know what, Damien?” Ms. Faulkner
responded. “A lot of adults would guess the same
thing. They would say, ‘A vacuum sucks the water
up into the glass.’ But I’ll tell you a saying that I
learned in my physics class in college: ‘Science never
sucks!’” The group erupted in laughter.
Ms. Faulkner had expected that one of her stu-
dents would suggest suction or a vacuum as the cause.
This happened every time she taught students about
FIGURE 3-1 Small inverted glass being submerged in water.
FIGURE 3-2 Large inverted glass being lifted out of the water.
Ready, Set, SCIENCE!: Putting Research to Work in K-8 Science Classrooms
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Foundational Knowledge and Conceptual Change 47
air pressure. Suction as an explanation made sense to
students because they’d had actual experience with
it. Drinking a milkshake through a straw, for instance,
felt like “sucking” liquid into your mouth.
Ms. Faulkner wanted to give her students some
time to think about this explanation, rather than
simply telling them it was not valid. She also wanted
them to question their assumptions and move beyond
the idea of suction just because it sounded scientific.
She told them that they would explore the issue in
depth, amazing themselves and their parents by the
end of the unit by knowing more about the physics of
air pressure than most college graduates do.
Then she briefly set out the plan of action. She
would do one more group demonstration. Then
they would work at different stations around the
room, called “situation stations,” in groups of four,
exploring different activities with air and water.
They would have a short amount of time to rotate
through all of the different stations, after which
they would choose one station to focus on. Each
group would put together a report for the rest of
the class, trying to explain what was going on at
their particular station.
After explaining the plan of action, Ms. Faulkner
took the top off a clean mayonnaise jar and passed
the jar around, asking the students to tell her what
was in it. They turned it upside down, examining
it closely. One student sniffed it and said,
“Nothing.” Another said doubtfully, “Air?”
“So we have two different ideas on the
table,” Ms. Faulkner said to the class. “What
do the rest of you think?” Surprisingly, the
students had a lot of different ideas about
this. Some thought both ideas were pos-
sible, because, as Jessa said, “air sort of is
nothing, except if the wind is blowing.”
As the students shared their ideas, Ms.
Faulkner recorded them on a large piece of chart
paper. She titled the chart “What We THINK We
Know About Air,” reminding them that this was
just the beginning of the investigation and their
ideas were sure to change. She explained that it
was important for them to record their ideas now
so they could look critically at them later and see
how they had changed over time, as more evidence
was gathered.
Finally, Ms. Faulkner said, “Let me do one more
demonstration that will add a little more data and
help us think about air.”
The demonstration was designed to show the stu-
dents that air took up space even though it was invis-
ible. Ms. Faulkner balled up a paper towel and stuck
it in the bottom of a large glass in such a way that it
would stay there and not fall out when turned. She
turned the glass upside down so the opening was fac-
ing the water in the tank (see Figure 3-4).
“I’m going to push the
glass down into the water.
What do you think will
happen? Will the paper
get wet?”
Everyone wanted to
talk at once. Ms. Faulkner
told each student to turn
to the person next to
them and discuss their
ideas. The room filled
FIGURE 3-4 Partially submerged upside-down glass with balled-up paper towel. Will the paper get wet?
FIGURE 3-3 Graduated cylinder being lifted out of the water.
Ready, Set, SCIENCE!: Putting Research to Work in K-8 Science Classrooms
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Ready, Set, SCIENCE!48
with talk as the students discussed with their partners
the experiment they were about to try. Ms. Faulkner
circulated around the room and listened in on differ-
ent conversations, noting a range of predictions.
After a few minutes, she brought the students’
attention back to the front of the room and asked
different partners to share their predictions, which
she wrote on the whiteboard. There were four dif-
ferent predictions:
1. The glass will be filled with water and the paper
will get wet.
2. A lot of water will go in the glass but the paper
will not get wet.
3. A little water will go in the glass but the paper
will not get wet.
4. No water will go in the glass and the paper will
not get wet.
Ms. Faulkner asked the students to vote, by a show
of hands, for the prediction they agreed with. She
explained that the voting was intended not as a basis
for determining correctness but to let everyone get a
sense of each other’s views of the most likely outcome.
Most of the students voted for Prediction 1, sev-
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.
“At first we thought the water would just go
into the glass, because, you know, it seems like
there’s nothing in there,” April said. “But then I
heard someone else saying they’d done it and no
water went in, and I changed my mind. I guess, like
Joanna said, there’s air in the glass and the air won’t
let the water in.”
Phuong spoke next. She was from Vietnam and
had lived in the United States for only two years, but
she was fascinated by science.
“I say 4. I don’t think the water will go in
because air is everywhere in the glass but not where
the paper is.”
Ms. Faulkner said, “So are you agreeing with
April? You’re both saying no water at all will go
in the glass and the paper will be dry?” Both girls
nodded.
Phuong continued, “I know air is real. It takes
up space and keeps water away from the paper.”
Ms. Faulkner asked for someone who had voted
for Prediction 3—predicting that a little water
would go into the glass—to explain their reasoning.
Joanna volunteered.
“Well, actually, I think this is probably wrong,
but me and Tanika were thinking that water is
heavier and has more force than air, and it might
force the air into a smaller and smaller space,
and even squish up the paper. But we agree with
Juanita and April. We’re pretty sure the paper
won’t get wet.”
Finally Ms. Faulkner did the demonstration. The
students watched, craning their necks and getting
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Foundational Knowledge and Conceptual Change 49
out of their seats to see the
aquarium, as she pressed the
upside-down glass slowly into the
water (see Figure 3-5).
It was difficult to see what was
happening because everything
looked blue. One of the students
pointed out that the paper wasn’t
getting wet, and the water went
only a little way up into the glass.
Someone else noticed that the
farther down into the water the
glass was pushed, the more water
went into it.
Ms. Faulkner pulled the glass out of the water,
took out the paper, and showed it to everyone.
It was completely dry! To prove it, she passed the
paper around to each student.
“So what have we figured out with this experi-
ment?” Ms. Faulkner asked. “Which prediction fits
the results the best, and why didn’t the paper get
wet? Go back to your seats and let’s talk about this.”
As soon as he sat down, Jeremy waved his hand
excitedly. Ms. Faulkner waited patiently for more
hands to go up. After about 10 seconds she called
on Tanika, who didn’t typically volunteer to speak.
“I think what we figured out is that the glass
has air in it and that the air keeps the water out,”
said Tanika. “Even though you can’t see it, it’s there.
And the reason the water went in a little, is like
what Joanna and I were saying, that the water is
maybe stronger than the air and kind of forces it
into a smaller space.”
“Can you say more about that?” asked Ms.
Faulkner.
“Maybe it’s like forcing a suitcase closed. You
press all the clothes down and even though it’s the
same amount of clothes, they take up less space.”
“That’s a really interesting way of thinking about
the same amount of stuff taking up less space,”
said Ms. Faulkner. “Let me see if I understand what
you’re saying. Are you saying that the air is getting
pressed up by the water, or compressed?”
Tanika nodded. “It’s like the air is getting
squished.”
Ms. Faulkner added the words “air is squishable
or compressible” to the “What We THINK We Know”
chart.
“Are there any other things we think we know
about air? Turn to the person sitting next to you
and talk for a minute about both of the demos
we’ve done. I want you to think about anything you
think you know about air. And talk about what the
bases for your claims about air are and how certain
you are about your ideas.”
Ms. Faulkner circulated among the students.
Everyone seemed to be talking, even students who
were usually reluctant to speak in a large group.
After calling the group back into session, she
decided to start with Jorge and Salizar, who felt cer-
tain that air was everywhere. She’d overheard them
speaking both in English and Spanish, and she’d
heard the word moléculas. She called on Jorge, the
quieter of the two, to explain what he and his part-
ner had come up with. Ms. Faulkner stood poised to
write on the “What We THINK We Know” chart, and
she reminded them again that these were just “first
draft” ideas, as she called them, that would probably
change a lot over the course of the unit.
Jorge spoke first. “Me and Salizar, we think air is
everywhere. Pequeñitos, moléculas.”
“I read in a book that molecules are really, really
small, too small to see without a microscope,” Salizar
said.
Ms. Faulkner wrote, “Air is everywhere, made up
of tiny molecules.”
Other students shared their ideas. Joanna spoke
for herself and Sherrie.
“Well, we sort of agree and sort of disagree.
We don’t think there’s air in space. Maybe there’s
FIGURE 3-5 Fully submerged glass: only a small amount of water gets in.
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air everywhere on earth, but not really everywhere.
We’re not completely sure if there’s air on the
moon, but we’re pretty sure there’s no air in space.
That’s why astronauts have to wear spacesuits.”
Everyone laughed.
Ms. Faulkner said, “Do you want me to change
our ‘What We THINK We Know’ chart?”
Jorge suggested adding “on earth” to “air is
everywhere.”
Shanita went next. “Air 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 can’t remember the difference between molecules
and atoms.”
Ms. Faulkner recorded these ideas, with question
marks next to “moon” and “atoms.” She felt the class
had made a great start. She directed them to a much
smaller wall chart, which showed their eight assigned
groups and the stations they’d specialize in. Around
the room were four very different set-ups, each involv-
ing air and water, making use of soda bottles, cups
and paper, straws, and large and small graduated cyl-
inders. She told her students they would have 5 min-
utes to spend at each of the four different stations.
They would then have 15 additional minutes to spend
at the station they would specialize in, and they would
continue the next day as well. Because there were
two different versions of each station, each of the
eight groups had its own set-up to explore in depth.
For the next 20 minutes, the students moved
from station to station in 5-minute blocks, reluctant
to leave each station when Ms. Faulkner’s timer
rang. When it was time to specialize, the students
settled around their designated stations and began
working. They took notes and drew pictures in their
lab notebooks, talking excitedly.
After 15 minutes, the bell rang. The students
were so engrossed in their stations they didn’t want
to stop. Ms. Faulkner was pleased and told them
they’d have more time the next day.
Over the next several days, each of the groups
attempted to explain what was happening at their
specific station. Each group developed a poster
that showed the demonstration in action and
tried to explain what was pushing what. Groups
presented to the class, and the students in the
audience responded with questions, challenges,
comments, and suggestions based on what they
had discovered at their own stations. Ms. Faulkner
made sure that the discussion stayed focused on
what was pushing what, in what direction, and on
what was causing change to occur.
After the last group presented, Ms. Faulkner
told the students she wanted to try to consolidate
their findings. The “What We THINK We Know”
chart was now full of new notes that the students
had added on their own, such as “air pushes up
and down and sideways,” “air has more force than
water,” and “air is squishable and can be made
smaller.” There were still, not surprisingly, several
explanations that used the notion of a vacuum or
suction.
Ms. Faulkner told the class that she was going to
start a chart called “Wall of Accepted Scientific Facts.”
“These are ideas about air that are currently
accepted as fact by the scientific community,” she
said. She pointed out that some of the facts were
the same as the ideas the students themselves had
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Foundational Knowledge and Conceptual Change 51
come up with, while others had taken scientists
hundreds of years to figure out. Some ideas, she
explained, might be hard for them to believe.
“I’m going to put up these facts, and we’re
going to see if we understand and accept them or
if we still have questions.” She told the class that
100 years ago a wall of facts about air would have
looked different, and it might look a bit different
100 years from now. “We still might want to add
to these, or rephrase them a bit as we continue our
unit, but these have a different status than the ideas
in our “What We THINK We Know” chart.”
Of the facts she put on the “Accepted Facts” chart
was one they’d already proposed—that air was all
around them, even though they couldn’t see it. She
confirmed that it was made up of tiny, tiny particles—
air molecules—so small they couldn’t be seen with a
regular microscope. As Shanita had said, air molecules
are constantly moving, very fast, in every direction.
Ms. Faulkner demonstrated this fact, pointing up
under her chin, pressing on the outside of her nose,
even on the inside of her nostril. She explained
that the air was pressing equally everywhere, on
the front and back of her ear lobe and on the out-
side of their noses as well as the inside. “Otherwise
your nostrils would collapse (she pressed her nostrils
closed) and you wouldn’t be able to breathe! So
there’s just as much air pressure on the inside of
your nostril as on the outside. If something is not
moving, it doesn’t mean that there’s no air pressure.
It means the forces of the air are balanced—pushing
equally in all directions. So air molecules are bounc-
ing every which way—down, sideways, up—on every
square inch of my body. But here’s something really
important. Scientists don’t say that the air molecules
want to move or decide to move. They just move.
They don’t want or try or desire to move. There’s
no intention or knowledge. It’s not like they know
there’s a door open and decide to go out the door.
Instead, they get pushed by another molecule and
hit a wall, bounce off, and by chance, they bop out
the door.” She wrote on the “Accepted Facts” chart:
• Air molecules are constantly moving, but without intention or knowledge.
• Air molecules are moving very fast in every direc- tion, and they don’t stick to one another, so they
can’t pull; they only push.
Then Ms. Faulkner added some more “surpris-
ing facts,” as she called them. She told the kids
that scientists often say we live at the bottom of an
ocean of air. “Scientists think of both air and water
as fluids. Fluids push in every direction—up, down,
and sideways—just like you saw in your stations.
And with both air and water, there’s more push,
more force, the deeper down you go. Remember
when you found that it got harder and harder to
push the drinking glass into the aquarium?” The
students nodded.
Shanita said, “Oh yeah, and remember how
we pushed an empty, upside-down glass into the
aquarium and the further down we pushed it, the
more the air got squished, or um, compressed? It
seemed like the water had more force the deeper
in the tank we went.”
“That’s another demonstration of the way that
the pressure in a fluid is greater the deeper down
you go,” Ms. Faulkner said. “And air is also a fluid.
The air molecules at the bottom of the ‘ocean of air’
are more squished together, or compressed, at sea
level because of the weight of all the air molecules
above them. In fact, at sea level, there’s 14.7 pounds
of air pushing on every square inch of your body!
Who can think of something that weighs that much,
almost 15 pounds?”
Eriziah said, “I have a 15-pound dumbbell at
home, and man that thing is heavy!” “Maybe
two gallon jugs of water one on top of another?”
Shanita volunteered.
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“Yes, but I’m talking about 14.7 pounds per
square inch, don’t forget,” said Ms. Faulkner. An
adult man has about 100,000 pounds of air, pushing
in every direction, on his body, up, down, sideways.”
She drew a square inch on her arm in blue magic
marker. “There’s 14.7 pounds, almost 15 pounds, of
air pressing down right here.”
“How come we can’t feel it?” Eriziah asked.
“Great question.” Ms. Faulkner said. “We can’t
feel it because we’re used to it. Our bodies—and every
living thing on earth—have evolved to live under these
conditions. So it’s normal for us. But the change in
air pressure is why your ears pop when you hike up
a mountain or fly in a plane. If you took an inflated
balloon that you blew up here, where we’re close to
sea level, and carried it all the way to Denver, which
is a mile above sea level, the balloon would be larger
in Denver because there’d be fewer air molecules hit-
ting the balloon on the outside, so there would be less
resistance against the molecules inside the balloon.”
A few of the students were beginning to think
about the first demonstration again, which many
still explained as having to do with suction.
“Wait a second,” Damian said. “You’re saying the
water is pushed into the glass, not sucked in?”
Ms. Faulkner asked if anyone could put into
their own words what Damian had said. Eriziah
wanted to try.
“Damian said the air wasn’t sucked into the glass
like with a vacuum, like he first thought it was.”
Ms. Faulkner nodded. “But why can’t the water
get sucked into the glass? Why can’t the air in the
glass suck up the water?”
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. “Is it because the
air molecules are moving so fast, like it says on the
wall of facts, they can’t pull, they can only push?” She
paused. “So air can’t pull or suck? It can only push?”
“I’m getting it, I think,” said Damian. “The
water is pushed into the glass by the air pressing
down on the surface of the water in the aquarium?
It’s like the air is forcing or squirting the water up
into the glass. Like if you slap your hand down on
water, it sort of splashes up?”
“Can anyone remember how much pressure
there is, how much force there is on every square
inch of the water in the fish tank?”
Jorge looked up at the wall of facts and said, “14.7
pounds per square inch of air pressing on the water.”
Then Ms. Faulkner gave them an example, which
she sketched on the board (replicated in Figure 3-6).
If instead of using a regular glass, upside down, to
pull out of the aquarium, they used a glass that had a
one-square-inch opening, like a rectangular bud vase,
the water in the vase would weigh however much a
column of water one inch by one inch weighs. That
depends, of course, on the height of the column of
water, because the more water in the column, the
more it would weigh. Still, there was no way that
the water in a column of 5 inches would weigh 14.7
pounds. As a result, the air pressure on the surface of
the water would keep the water in the glass.
Ms. Faulkner’s diagram looked something like this:
Phuong asked a question that Ms. Faulkner wasn’t
anticipating. “How much would the water weigh
in that bud vase if it was like 5 inches high?” Ms.
FIGURE 3-6 Ms. Faulkner’s diagram of air pressure.
14.7 pounds per square inch of air pressure
weight of column of water in 1-inch-square bud vase
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Foundational Knowledge and Conceptual Change 53
Faulkner decided she would follow Phuong’s lead and
take a bit of a detour to explore her question. She
sensed that figuring out the weight of a column of
water that was one inch by one inch might help her
students, down the road, in thinking about pressure
more generally as a ratio of force per area.
She asked the students to propose ways they could
investigate the answer to Phuong’s question. Again
she wrote proposals, figuring someone might come up
with a solution that the class could work on as home-
work. A number of suggestions were proposed:
Get a hollow one-cubic-inch container and weigh
it before and after you fill it with water and sub-
tract the weight of the container. Then multiply
that by 5, for the 5-inch height.
Measure the aquarium carefully to find out how
many cubic inches it holds, and then weigh it
both empty and filled with water. Then subtract
the container and divide the total by the number
of cubic inches. Multiply that by 5.
Ask a scientist!
Get a syringe and fill it with the number of milli-
liters of water that would equal a cubic inch of
water and weigh the syringe with and without
water.
Finally, much to Ms. Faulkner’s surprise, Salizar
called out, “Just Google it!” He walked over to the
computer and “Googled” weight of cubic inch of
water and less than 5 seconds later said, “I’ve got it!
Water weighs 0.036 pounds per cubic inch or 8.33
pounds per gallon.” Ms. Faulkner wrote down the
results. Shanita added, “That’s way less than the
14.7 pounds per square inch that the air is pressing
down with.”
Ms. Faulkner directed the students back to
Phuong’s original question. “How much would the
water in this 5-inch-high bud vase weigh? Everyone
take a minute to figure it out and then talk to the
person sitting next to you.”
There was silence for a few moments as students
worked alone, and then partner talk took off. Two
students showed their work—drawing 5 cubic inches
on top of one another and multiplying Phuong’s
results of 0.036 pounds per cubic inch by 5 inches,
with the answer of 0.18 pounds of water. There was
uniform agreement that this was how much the 5-
inch column of water would weigh.
Jason asked if there would be more force push-
ing the water into the glass in a larger aquarium
because there would be more total pounds of air on
the surface of the water. “Or what if it was like a
huge swimming pool full of water?”
“Jason has asked a really important question,”
Ms. Faulkner said. “He asked if there would be
more air pressure pushing down on the water in a
bigger tank, or a swimming pool, or an ocean? The
answer that the science community would give is
that the pressure would be the same on every square
inch, so the amount of water doesn’t matter. It’s
the weight of the air per unit area.” She reminded
them that pressure is always a ratio, a relationship
between two things—force per area.
The concept of a ratio, Ms. Faulkner knew, was
an important one in science, and the class had spent
a great deal of time learning about ratios and using
different analogies to understand them.
This time, Ms. Faulkner used an analogy that
related directly to pressure. She asked her students
to imagine all of the girls in the class walking across
a lawn in high heels versus flat-soled running shoes.
Everyone could imagine right away that the girls
would make a deeper indentation in the dirt if they
were walking in high heels.
“You weigh the same, but the pressure on the
high heel is pressing on a much smaller area. Pressure
is a ratio: how much force there is in relationship
to how much area there is.” Then Ms. Faulkner
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Ready, Set, SCIENCE!54
brought them back to the situation in the aquarium.
“So even if the surface area of the water is huge,
what matters is how many and with how much force
the air molecules pound each square inch of the
surface of the water. Wherever you are, at sea level
or in the mountains, you don’t have to calculate
the surface area in a container, or in a swimming
pool, or in a huge lake, because at the same eleva-
tion, every single square inch has exactly the same
amount of air pressure on it.”
After a moment, Monica asked, “How tall a glass
could we pull out of the aquarium? How far could
the column of water be pushed up, by air?”
“Could it go all the way up into space?” some-
one else asked.
Salizar quickly responded, ”It couldn’t go that far
up because there’s only 14.7 pounds per square inch
pushing down. If the water weighed more than 14.7
pounds per square inch, it wouldn’t stay up. The
water would win in the battle of the forces!”
“So how far can the air push the water up?”
Monica asked again.
“I don’t know the answer to that question,” Ms.
Faulkner admitted. “But I’m sure we can figure it
out. Any ideas about how to get started? What
would we need to know?”
There was silence. Finally, Tanika said, “How
many cubic inches of water does it take . . . um,
to weigh more than the air pressure—like 14.7
pounds?”
As if finishing Tanika’s sentence, Monica con-
tinued, “Like how many cubic inches of water can
push down on that spot to outweigh the air pressure
that’s forcing the water up?”
Phuong said, “I think I get it. It’s like the air
pressure is pressing down on the surface of the
aquarium, everywhere, like a piece of plywood
pressing down with a lot of force, like a lot of force.
And then we cut a hole in the plywood, like a one-
square-inch hole. And right there, on that square
inch, there’s no air, no nothing, I mean no pressure
pushing the water down. So the water would squirt
up through the hole! If we had the one-inch glass
there, the bud vase thingy, then the water would
squirt up into it. When the water column goes
higher and higher it gets heavier and heavier, and
at some point, eventually, the water will weigh as
much—down—as the air is pushing up. That’s as
far as it could go.” After a long pause he said, “So
how many of Salizar’s little cubic inches could we
pile up on top of one another? How many would
equal up to 14.7 pounds?”
“Phuong’s on the right track when she asks
how many of Salizar’s little cubic inches could we
pile up on top of one another to equal the air pres-
sure at 14.7 pounds per square inch,” Ms. Faulkner
said. “It’s really a question of balancing forces. It’s
like a seesaw. We’ve got someone on one side who
weighs 14.7 pounds. That’s the air pressure. On the
other side, we’ve got a one-inch-square column of
water. With what we’ve figured out already, see if
you can figure out how tall that column of water
could be. And, even more interesting, see if you can
figure out a way we could test it to see if our calcu-
lations are right. Think about it tonight, and we’ll
talk about it tomorrow.”
By the next day, the class had calculated that
the air could hold up a column of water 34 feet tall.
They had come up with many different methods,
but the simplest was building on Salizar’s fact that
a cubic inch of water weighs 0.036 pounds. They
divided 14.7 pounds by 0.036 pounds (per cubic inch)
and came up with 408.3 cubic inches. That’s how
many cubic inches of water could be piled on top of
each other to equal 14.7 pounds. They then divided
that by 12 to determine the feet and got 34.03 feet.
Ms. Faulkner applauded her students’ hard work
and amazing results—they had truly changed their
conceptual thinking in many ways.
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Foundational Knowledge and Conceptual Change 55
Examining Conceptual Change in Molecules in Motion
In the “Molecules in Motion” 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 them—the first type of conceptual change described earlier in this chapter.
After eliciting ideas from the students for the “What We THINK We Know About Air” 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 something—something that took up space in an “empty” glass. “Something” 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 pressure—the 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. Faulkner’s 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
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Ready, Set, SCIENCE!56
make sense of processes in other domains. The foundation built in Ms. Faulkner’s classroom will be critical for their success in subsequent years.
What specific classroom activities and forms of instruction supported the students’ conceptual reorganization? First, it’s important to note that Ms. Faulkner began the unit by recognizing and honoring students’ 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, “squish- able.” They saw that the water entered the glass a little bit—evidence that the water was forcing the air into a smaller space. They couldn’t 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 explore—and revisit in new forms—some 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 field—the deeper down, the more pressure—in 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 one’s 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
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Foundational Knowledge and Conceptual Change 57
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 “looks like” 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 children’s understanding of the material world is based on their perceptual experiences—on 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 “nothing at all” 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 “core concepts” have great explanatory power and can be built on in increasingly complex ways from year to year. In the next chapter, we’ll see how this process can work, not only for atomic-molecular theory but also throughout the disciplines of science.
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Ready, Set, SCIENCE!58
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-
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NJ: Lawrence Erlbaum Associates.
Inagaki, K., and Hatano, G. (2002). Young children’s naïve 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 children’s science instruc-
tion. Review of Educational Research, 65, 93-127.
Metz, K.E. (2004). Children’s understanding of scientific inquiry: Their conceptualization
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