PART III
Supporting Science Learning

In the preceding chapters we have developed a complex picture of student learning in science. It shows that children come to school with powerful and sophisticated ways of reasoning about the material world that enable them to function effectively in many arenas. It also shows that their reasoning is limited in important ways; it is based on a limited range of experiences, and it lacks the predictive and explanatory power of expert scientific reasoning. Finally, this picture shows that with appropriate instruction children can make significant progress toward more sophisticated scientific reasoning, and we know some key principles that inform the design of that instruction. These results are products of a sustained dialogue among developmental and education researchers.

However, this research dialogue and its results have not significantly influenced science education policy and practice. This is in part because science education policy and practice are legitimately concerned with issues that are peripheral to the research dialogue; for example, by what scientific knowledge is most valued by the American public. In many cases, it is clear that policy and practice could be more effective if they were influenced by the research. Curriculum documents and textbooks fail to recognize the importance of children’s prior experience, underestimating both their capacities for reasoning and the difficulties posed by scientific conceptions. In instruction, knowledge and practice are separated in ways that diminish the power of scientific reasoning. Teachers must often rely on models of instruction that are demonstrably ineffective. Clearly, children in America would benefit if policy makers, curriculum developers, and practitioners made more effective use of research results.



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Taking Science to School: Learning and Teaching Science in Grades K-8 PART III Supporting Science Learning In the preceding chapters we have developed a complex picture of student learning in science. It shows that children come to school with powerful and sophisticated ways of reasoning about the material world that enable them to function effectively in many arenas. It also shows that their reasoning is limited in important ways; it is based on a limited range of experiences, and it lacks the predictive and explanatory power of expert scientific reasoning. Finally, this picture shows that with appropriate instruction children can make significant progress toward more sophisticated scientific reasoning, and we know some key principles that inform the design of that instruction. These results are products of a sustained dialogue among developmental and education researchers. However, this research dialogue and its results have not significantly influenced science education policy and practice. This is in part because science education policy and practice are legitimately concerned with issues that are peripheral to the research dialogue; for example, by what scientific knowledge is most valued by the American public. In many cases, it is clear that policy and practice could be more effective if they were influenced by the research. Curriculum documents and textbooks fail to recognize the importance of children’s prior experience, underestimating both their capacities for reasoning and the difficulties posed by scientific conceptions. In instruction, knowledge and practice are separated in ways that diminish the power of scientific reasoning. Teachers must often rely on models of instruction that are demonstrably ineffective. Clearly, children in America would benefit if policy makers, curriculum developers, and practitioners made more effective use of research results.

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Taking Science to School: Learning and Teaching Science in Grades K-8 One key reason that policy makers and practitioners fail to do this is the complexity and fragmentation of the research literature. The studies we review in this report, drawn from a range of literatures, were mostly short in duration and limited in scope, focusing on a few students or a few classrooms, learning about some small part of the vast domain of science. These studies are also embedded in a research discourse that is complicated and often inaccessible to nonspecialists. There are reasons for the difficulty of the discourse. Science learning really is complex, and the research on learning cannot be reduced to a few “what works” bullet points without losing much of its value. In Part III, we begin to take up the challenge of interpreting research on learning so as to inform policy and practice in science education. We begin in Chapter 8 with a proposal for reorganizing the K-8 science curriculum in a way that is more aligned with current understanding of children’s learning in science. The hallmark of this approach is the investigation of a smaller set of core ideas and practices in science over an extended period of time. Instructional sequences that weave together the four strands and thereby coordinate conceptual learning with science practices and discourse require adoption of curriculum and assessment models that function over months, years, and grade bands. In Chapter 9, we turn to a consideration of instruction and assessment. Our review of the research on learning combined with the four-strand framework has implications for how one thinks about the design of the classroom learning environment. Research on learning shows how important it is to include learning opportunities that develop children’s abilities to obtain and reason with evidence, to develop and evaluate explanations, to develop and evaluate standards of evidence, to represent and communicate scientific data and ideas, and to engage in argumentation practices. Thus, although we argue in Part II that children are very capable learners, this does not preclude the fact that carefully thought out instructional supports and mediation are needed to help develop scientific practices and ways of knowing. In Chapter 10 we broaden our view to consider the knowledge and tools that teachers need in order to enact high-quality instruction. We analyze the knowledge base of current in-service K-8 science teachers, and we describe what these teachers would need to know about science, teaching, and learning in order to teach science as we have discussed it in this report. We also examine the means of advancing teacher knowledge through a range of opportunities to learn. These include programs of professional development, workplace learning, and use of instructional systems that provide clear instructional guidance for teachers and provide them with timely feedback on their teaching and strategies for improvement.

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Taking Science to School: Learning and Teaching Science in Grades K-8 8 Learning Progressions Main Findings in the Chapter: Many standards and curricula contain too many disconnected topics that are given equal priority. Too little attention is given to how students’ understanding of a topic can be supported and enhanced from grade to grade. As a result, topics receive repeated, shallow coverage with little consistency, which provides a fragile foundation for further knowledge growth. Findings from research about children’s learning and development can be used to map learning progressions in science. That is, one can describe the successively more sophisticated ways of thinking about a topic that can follow and build on one another as children learn about and investigate a topic over a broad span of time (e.g., 6 to 8 years). Steps in these progressions are constrained by children’s knowledge and skill with respect to each of the four strands. Reaching the hypothetical steps described in the progressions is also dependent on teachers’ knowledge and the effectiveness of their instructional practices. Learning progressions are a promising direction for organizing science instruction and curricula across grades K-8. However, further research and development is needed to identify and elaborate the progressions of learning and instruction that can support students’ understanding of these core ideas across the disciplines of science. Science learning presents a special challenge to educators because of both the diversity and the complexity of mature scientific knowledge and the fact that it rests on organized conceptual frameworks and sophisticated

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Taking Science to School: Learning and Teaching Science in Grades K-8 knowledge construction and evaluation practices that are fundamentally different from the concepts and meaning-making practices that children bring to school. Although children bring a wealth of resources to the science learning task (see Part II), those resources must be built on, enriched, and transformed if they are to learn science with understanding. One challenge is to understand what is most important to teach (given limited time and resources) at the K-8 level: What might be the most important “core ideas” that both empower students to understand the distinctive value of science and prepare them for further learning in science? Another challenge is to understand the pathways—or learning progressions—by which children can bridge their starting point and the desired end point. Given the complexity and counterintuitive nature of the end point, such learning must necessarily occur over a long period of time, work on multiple fronts, and require explicit instruction. Yet at present, curriculum sequences are not typically guided by such long-term vision or understanding, nor is there clear agreement, given the wealth of scientific knowledge, about what might be truly foundational and most important to teach. In this chapter we develop the idea of learning progressions as an approach to research synthesis that could serve as the basis for a dialogue that includes researchers, assessment developers, policy makers, and curriculum developers. Learning progressions are descriptions of the successively more sophisticated ways of thinking about a topic that can follow one another as children learn about and investigate a topic over a broad span of time (e.g., 6 to 8 years). They are crucially dependent on instructional practices if they are to occur. In the chapter we (a) discuss key characteristics of learning progressions, contrasting them with current approaches to defining curriculum and assessment and describing some of the challenges in developing them; (b) use current work on a learning progression as an example of both the problems and possibilities in this approach; and (c) discuss implications and further questions. CURRENT APPROACHES IN POLICY AND PRACTICE At present, most decisions about instruction and curriculum sequences in science have not been guided by a long-term understanding of learning progressions that are grounded in the findings of contemporary cognitive, developmental, education, and science studies research (much of this research is reviewed in Part II). Two approaches that have influenced policy and practice are (1) approaches characterizing learning in terms of science process skills and (2) approaches to listing important conceptual knowledge in standards documents.

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Taking Science to School: Learning and Teaching Science in Grades K-8 Science Process Skills Some scope and sequence suggestions that have been influential in the design of elementary science curricula and texts (e.g., the task analyses of the processes of science and of learning done by psychologist Gagne, which led to the sequence of process skills proposed by the curriculum Science: A Process Approach in the 1960s) are based more on rational task analyses than on findings about how children learn meaningful scientific concepts. These proposed “learning hierarchies” focused on building competence with domain-general processes rather than helping children build frameworks of interrelated science concepts. They had an appeal to teachers and curriculum developers because they broke complex tasks down into simpler elements, identified 14 basic process skills that were proposed to develop in a certain sequence and to underlie scientific thinking, and provided many specific exercises for children to practice these skills. But because they ignored the crucial role of meaning, content, and context and treated science instead as a series of disembodied “skills,” they were often carried out as meaningless procedures (Baroody et al., 2004; Mintzes, Wandersee, and Novak, 1997). For example, children practiced making observations of a variety of types or making measurements without a concern for understanding what they were observing or measuring. As we have shown in Chapter 5, knowledge is intimately intertwined with scientific reasoning. Ultimately, however, children failed to develop meaningful understanding under science-as-process instructional programs, and researchers recognized how little these domain-general “skills” actually generalized. Another criticism of these scope and sequence proposals was that they were based on faulty developmental assumptions about children’s reasoning and learning capacities (e.g., that young children are concrete rather than abstract thinkers and capable only of observation rather than explanation; Metz, 1995; see our discussion in Chapter 3). Consequently, only a small subset of science process skills (e.g., observing, measuring, predicting) were practiced in the early elementary grades, with more advanced skills (e.g., formulating hypotheses, controlling variables, interpreting data) introduced only in the upper elementary and middle school grades, and many other important sense-making practices of science (practices involving modeling, representation, discourse, and argumentation) were omitted entirely. Given that current research has highlighted the interaction between domain-specific knowledge and reasoning, the importance of modeling, representational practices, and discourse in promoting conceptual understanding, and the capacity of young children to engage in a wide range of these meaning-making practices, a very different approach to describing learning sequences is needed, one that that is more centrally grounded in building an understanding of conceptual frameworks (see discussion of this issue in Part II).

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Taking Science to School: Learning and Teaching Science in Grades K-8 Although Gagne’s original formulation of science as a collection of content-free process has largely been rejected by science educators, its legacy persists in both policy and practice. Many textbooks and curriculum documents still have separate sections on scientific inquiry, science processes, or “the scientific method.” Many classroom teachers follow the lead of these resources, teaching skills and inquiry techniques separately from the conceptual content of their courses. Curriculum Standards Other approaches to guiding curriculum include writing national, state, and district science standards. These standards are an important start (at codifying values), but they generally were based on values and the personal experiences of their writers rather than research on children’s learning or detailed conceptual analyses of scientific knowledge and practice. Current national, state, and district standards do not provide an adequate basis for designing effective curriculum sequences for several reasons. First, they contain too many topics without providing guidance about which topics may be most central or important. National standards such as the National Science Education Standards (NSES) (National Research Council, 1996) or Benchmarks for Science Literacy (American Association for the Advancement of Science, 1993) do help to pare down the number of science topics to be covered. However, they still retain many more topics than can be covered and do not identify the most central or important topics. For example, a comparison of the NSES with curriculum in high achieving countries that participated in the Third International Mathematics and Science Study (TIMSS) reveals that the NSES call for much broader coverage of topics with little sequencing across grades (Schmidt, Wang, and McKnight, 2005). Second, they typically present the key ideas as simple declarative statements without explaining how those understandings need to be grounded in experience with the material world or in reasoning practices. Third, they are not sequenced in ways that recognize research on the development of children’s understanding. Project 2061’s Atlas of Science Literacy (American Association for the Advancement of Science, 2001) does provide a guide for interconnection between important concepts in science with some sequencing. The analysis is based primarily on the structure of knowledge in the disciplines of science with some attention to what scientific ideas children can understand at a given grade level. We propose a sequencing that is more deeply informed by research on children’s learning such that the sequences are grounded also in what we know about the ideas children bring to the classroom that can form the foundation for developing understanding of scientific ideas. As we explain later in the chapter, these foundational ideas sometimes do not closely resemble the scientific ideas they can support.

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Taking Science to School: Learning and Teaching Science in Grades K-8 Fourth, while they recognize the central role of involving students in the culture of scientific practice to build scientific knowledge, they do not fully articulate how students’ participation in science practices can be integrated with learning about science concepts. Finally, although many standards documents include at least the first three of the four strands of scientific proficiency that we use to organize this report, these strands are generally described separately, so the crucial issue of how advances in one strand are linked to and support children’s learning in the other strands is not addressed. Curriculum and Instruction in K-8 Science Classrooms As currently described and enacted in U.S. K-8 science classrooms, curriculum—the sequence and series of tasks and assignments posed to students—rarely builds cumulatively and in developmentally informed ways, from students’ early knowledge and resources toward scientifically accepted theories and concepts. Although there are some curricular materials that pursue this approach, they tend to cover a limited slice of content and are often restricted in duration to periods spanning a few to several weeks of instruction. It is highly unlikely that brief periods of uncoordinated instruction are going to achieve the goal of helping students generate a scientifically informed epistemology, a deep and well-structured knowledge base, and a firm understanding of the purposes and methods of science. Analyses of science curricula in the United States indicate that they are generally poorly designed for the purpose of effective knowledge building. Evaluations recently conducted under the leadership of the American Association for the Advancement of Science (AAAS) Project 2061 staff suggest that the major commercial textbook series, which do at least take a multiyear perspective to sequencing instruction, have major flaws of various kinds, including content, motivation, and attention to student prior conceptions (Kesidou and Roseman, 2002). The AAAS analysis indicates that curriculum is rarely framed around the big ideas. Indeed, the big ideas are largely lost in the curriculum. Roseman, Kesidou, Stern, and Caldwell (1999), authors of the AAAS report, concluded (p. 2): [T]he textbooks covered too many topics and didn’t develop any of them well. In addition, the texts included many classroom activities that either were irrelevant to learning key science ideas or didn’t help students relate what they were doing to the underlying ideas. Valverde and Schmidt’s (1997) comparison of U.S. science curriculum with the 10 countries performing best on the tests of science achievement in the Trends in International Mathematics and Science Study provide further support for the AAAS conclusions, as well as the results of these curricular

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Taking Science to School: Learning and Teaching Science in Grades K-8 patterns on student learning. They found that U.S. science curricula constitute a relatively extreme case of broad and superficial coverage, with little attention to building links across concepts. The U.S. science texts covered many more topics than the texts of the high-achieving countries. In their words, “breadth of topics is presented in these textbooks at the expense of depth of coverage. Consequently, U.S. textbooks are limited to perfunctory treatment of subject matter” (p. 62). More specifically, Valverde and Schmidt point to the failure of U.S. science curriculum to build connections between the abundant knowledge pieces presented in the curriculum and the resultant epistemic messages this conveys about the structure of the discipline (pp. 62): The unfocused curriculum of the United States is also a curriculum of very little coherence…. U.S. textbooks and teachers present items one after the other from a laundry list of topics from state and local district guides …. This is done with little or no regard for establishing the relation between various topics or themes on the list. The loss of these relationships between ideas encourages children to regard these disciplines as no more than disjointed notions that they are unable to conceive of as belonging to a disciplinary whole. An increasingly popular approach to science curriculum in U.S. school districts is the use of science kits. Individual kits may provide students with a 6- or 8-week experience that, in some cases, provides a coherent set of experiences that build logically. While kits can bring some coherence to science curriculum (at least at the level of the unit), the cumulative effect of a kit-based approach to science can be very problematic. In many cases, students receive a series of brief exposures to a collection of unrelated topics (the rainforest, rocks and minerals, weather) presented in modular units or kits. The sequence of presentation hardly matters, as the ideas do not build in any meaningful way. Although we know of no research that has explicitly probed the learning research base of kits, their presentation of science topics as essentially interchangeable and noncumulative raises serious concerns. Kit-based curricula appear to be sensitive to a number of practical concerns, including variability in standards from locale to locale, so that a teacher can never count on a student’s having knowledge prerequisite to a new set of concepts. It also maximizes flexibility, so that teachers with low content knowledge can easily skip over topics that are too unfamiliar. However, it also sacrifices the potential long-term benefits of carefully crafted curricula that strategically build on student skills and their knowledge base. Curriculum needs restructuring to much more adequately support building robust science knowledge. It is not sufficient to teach lots of pieces of science knowledge. The curricular scaffolding of robust knowledge in the

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Taking Science to School: Learning and Teaching Science in Grades K-8 form of cohort knowledge structures, organized around core ideas, is critical for supporting science proficiency (see Chapter 4 for discussions of conceptual change and building knowledge structures). K-8 science curriculum needs to much more adequately build robust science knowledge of this form. Deciding how research can guide standards and curriculum has also proved to be a difficult process. Which studies are trustworthy? Should one take evidence that few students have learned a concept at a given age as evidence that few students can learn? Conversely, should one take evidence of successful teaching in a few classrooms as justification for including content in standards? DEFINING LEARNING PROGRESSIONS Learning progressions are descriptions of the successively more sophisticated ways of thinking about a topic that can follow one another as children learn about and investigate a topic over a broad span of time (e.g., 6 to 8 years). They are crucially dependent on instructional practices if they are to occur. That is, traditional instruction does not enable most children to attain a good understanding of scientific frameworks or practices, but there is evidence that the proposed learning sequences could occur with appropriate instructional practices. The more effective instructional practices aim to build understanding through involving students in a variety of practices, including gathering data through observation or experiment, representing data, reasoning—with oneself and others—about what data mean, and applying key ideas to new situations. At the same time, bringing about understanding of scientific frameworks is difficult, so innovative instructional practice is most effective when sustained over a period of time. The timescale of most innovative teaching interventions has typically been relatively short (on the order of 2 or 3 months for a specific topic). Thus, our ideas about longer term learning progressions are conjectural—ideas about how understanding could be developed given sustained and appropriate instructional practices—while at the same time based on research syntheses and open to empirical investigation in future research. That is, they are plausible hypotheses, greatly constrained by the findings of research. More specifically: Learning progressions are anchored on one end by what is known about the concepts and reasoning of students entering school. There is now a very extensive research base at this end (see Chapter 3), although much of it is not widely known or used by the science education community, which often relies on older (outdated) characterizations of preschool and elementary schoolchildren’s competence from the (earlier) developmental literature.

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Taking Science to School: Learning and Teaching Science in Grades K-8 At the other end, learning progressions are anchored by societal expectations (values) about what society wants middle school students to understand about science. They are also constrained by research-based conceptual and social analyses of the structure of the disciplinary knowledge and practice that is to be learned. Analysis of disciplinary knowledge is important in helping to identify the core ideas in science—those of greatest explanatory power and scope—that it may be most important to teach, because they provide central frameworks for further learning. Examples of such core ideas are the atomic-molecular theory of matter and evolutionary theories of life’s diversity. In addition, analysis of disciplinary knowledge helps identify the network of ideas and practices on which those core ideas rest, and hence what will be important component ideas to develop as part of their construction. Learning progressions propose the intermediate understandings between these anchor points that are reasonably coherent networks of ideas and practices and that contribute to building a more mature understanding. It is important to note that some of the important precursor ideas may not look like the later ideas, yet they crucially contribute to their construction. For example, realizing that objects are composed of materials and have some properties because they are made of that material is a critical first step toward understanding atomic-molecular theory. By thinking hard about what initial understandings need to be drawn on in developing new understandings, learning progressions highlight important precursor understandings that might otherwise be overlooked by teachers and educators. The intellectual exercise of constructing learning progressions requires one to synthesize results from disparate (often short-term) studies in ways that begin to address questions of how longer term learning may occur; learning progressions suggest priorities for future research, including the need for engaging in longer term studies based on best bets suggested by these research syntheses; and they present research results in ways that make their implications for policy and practice apparent. Ultimately, well-tested ideas about learning progressions could provide much needed guidance for both the design of instructional sequences and large-scale and classroom-based assessments. Key Characteristics The learning progression approach has four characteristics that are mostly absent from accounts of domain-general developmental sequences and current standards documents.

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Taking Science to School: Learning and Teaching Science in Grades K-8 Use of the current research base: We suggest that learning progressions should make systematic use of current research on children’s learning (reviewed in Part II) to suggest how well-grounded conceptual understanding can develop. For more on how the research can be used, see the example developed below. Interconnected strands of scientific proficiency: Learning progressions consider the interaction among the strands of scientific proficiency in building understanding (know, use, and interpret scientific explanations of the natural world; generate and evaluate scientific evidence and explanations; understand the nature and development of scientific knowledge; participate productively in scientific practices and discourse) and always involve students with meaningful questions and investigations of the natural world. Organization of conceptual knowledge around core ideas: Learning progressions recognize that the first strand of scientific proficiency (understanding and using scientific explanations) involves far more than learning lists of facts. Scientific understanding is organized around conceptual frameworks and models that have broad explanatory power. The purpose of concepts is to extend understanding—to allow one to predict, understand, and explain phenomena one experiences in the world—as well as to solve important problems. It is therefore important to explicitly recognize these frameworks and to help children develop them through instruction that involves model building and conceptual change. Recognizing multiple sequences and web-like growth: Learning progressions recognize that all students will follow not one general sequence, but multiple (often interacting) sequences around important disciplinary-specific core ideas (e.g., atomic-molecular theory, evolutionary theory, cell theory, force and motion). The challenge is to document and describe paths that work as well as to investigate possible trade-offs in choosing different paths. Design Challenges In the development of learning progressions that are research-based and reflect the variety of ways that children can learn meaningfully about a topic, there are three challenges, none of which can be completely overcome with the existing research base: (1) describing a student’s knowledge and practice at a given point in the learning progression, (2) describing a succession of ways students can understand a topic that show connections between ways and respect constraints on their learning abilities, and (3) describing the variety of possibilities for meaningful learning for students with different personal and cultural resources or different instructional histories. We discuss each of these challenges below.

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Taking Science to School: Learning and Teaching Science in Grades K-8 students have to have developed some clear expectations about materials and how they should behave. These are exactly the kinds of expectations that they have been developing in grades 3-5, as they are learning to measure both weight and volume and coming to understand that matter has weight and takes up space. There are a large number of situations in which this basic data pattern (of volume change but weight conservation) can be readily observed by students. Some involve solids, some involve liquids, some involve gases, and still others involve a change of state. In the course of teaching, students should be exposed to all these situations. For starters, however, consider one phenomenon that research has shown to be especially intriguing and puzzling for middle school students and how it can be used to invite initial debate and discussion about whether matter is fundamentally particulate or continuous (Snir, Smith, and Raz, 2003). The phenomenon involves mixing two equal volumes of water and alcohol, which are both colorless liquids. If you mix a given volume of water (say 50 ml) with a given volume of alcohol (also 50 ml), the resultant mixture of water and alcohol is only about 96 ml, not 100 ml, which is what students would have expected. Students immediately suspect that some liquid has been lost in the transfer. To rule out this possibility, it can be shown that there has been no loss of material: the weight of the mixture is equal to the weight of the two component parts. In addition, to allow students to more fully study the mixing itself, the two liquids can each be colored (with different food coloring) so students can watch more clearly what happens as they mix. Just as before, they can collect data showing that the total weight, but not the total volume of the system has been conserved. They can also see that if the (blue) colored water is mixed with the (red) colored alcohol, the two liquids intermingle and intermix, turning a uniform purple throughout. A number of provocative questions can be raised about this simple demonstration, including: How can two (continuous) liquids intermix? Why is the volume of the mixture less than the sum of the volumes of its parts? Why is the weight of the mixture equal to the sum of the weights of its parts? Students are very intrigued (and surprised) by this demonstration, and in searching for possible explanations, they can be asked: What might matter be like at a very tiny scale (much too small to directly observe), in order for this to be? Students can consider a number of alternative models of the situation, based on different assumptions about what matter is like at such a small scale. For example: Would it be continuous all the way down (i.e., no

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Taking Science to School: Learning and Teaching Science in Grades K-8 gaps or breaks)? Would there be discrete but tightly packed particles (i.e., no spaces between the particles)? Would there be discretely spaced particles of different sizes? For each alternative, they can then work through the consequences of those assumptions—what would be predicted to happen in this situation—on each set of assumptions. They can then consider how well each imagined alternative can actually explain the three main facts. Note that, to even engage with this issue, students have to be able to imagine that if matter were repeatedly divided in half until it was in a piece too small to see, some matter would still be there—it wouldn’t simply disappear if it were no longer visible. Research has shown that as students move from thinking about matter in terms of commonsense perceptual properties (something one can see, feel, or touch) to defining it as a constituent, that takes up space and has weight, they are increasingly comfortable with making this assumption. In this way, the framework they are developing in grades 3-5 is preparing them for theorizing at this level. In addition, they need to engage in “hypothetico-deductive” model-based reasoning: they must conjecture about (and represent) what matter is like at a level that they can’t see, make inferences about what follows from different assumptions, and evaluate the conjecture based on its fit with a pattern of results. Significantly, two small-scale research studies have shown that middle school students are able to (enthusiastically) discuss these issues, especially when different models (for several puzzling phenomena) are implemented on a computer and they are put in the position of judging which models can account for the facts (Snir, Smith, and Raz, 2003). Indeed, this approach led students who had relevant macroscopic understandings of matter to see the discretely spaced particle model as a better explanation than alternatives (e.g., continuous models and tightly packed particle models). Furthermore, class discussions allowed students to make an important ground rule for evaluating models more explicitly: models were evaluated on the basis of their consistency with an entire pattern of results and their capacity to explain how the results occurred rather than on the basis of a match in surface appearance. In this way, discussions of these simulations were used to help them build important metacognitive understanding of an explanatory model. Describing and explaining the behavior of air or other gases—for example, understanding that (macroscopically) they compress and expand and searching for underlying (more microscopic) explanations of how that happens—provides another fertile ground for appreciating the explanatory power of assuming that matter is fundamentally particulate rather than continuous (Lee et al., 1993; Nussbaum, 1998). Of course, these investigations bear on students’ emerging ideas about the nature of matter only if they understand that gases are material, something the proposed learning progression recommends that students begin to investigate at the previous age band. At the same time, coming to understand the behavior of gases in particulate terms

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Taking Science to School: Learning and Teaching Science in Grades K-8 should help consolidate student understanding that gases are matter and enable them to visualize their (unseen) behavior. In other words, developing macroscopic and atomic-molecular conceptions can be mutually supportive. Direct support for this assumption was provided in a large-scale teaching study with urban sixth grade students that compared the effectiveness of two curriculum units. One unit focused more exclusively on teaching core elements of the atomic-molecular theory, without addressing student misconceptions about matter at a macroscopic level. The other included more direct teaching of relevant macroscopic and microscopic concepts and talked more thoroughly about how properties of invisible molecules are associated with properties of observable substances and physical changes. The latter unit led to much greater change in understanding phenomena at both macroscopic and molecular levels (Lee et al., 1993). Furthermore, as the extensive research of Nussbaum and colleagues with seventh and eighth grade students attests, such instruction is especially effective if students are involved in classroom debates and discussion about essential (metaphysical) ideas, alternative theories, and larger epistemological issues (Nussbaum, 1998). For example, how could a vacuum exist? Why wouldn’t matter be automatically sucked into empty space? If there are discretely spaced particles, what holds them together? How do particles move and interact (e.g., do they obey laws of mechanical causality)? Such classroom debate and discussion allow classroom experiments to become more meaningful and informative to students. In addition, thought experiments are used to help students contrast descriptions at the particulate and macro level. For example, students are asked to imagine that a small dwarf (tinier than the smallest particle of matter) stuck a needle into a particle of water or a particle of gas. Would water leak out? Would the gas burst out and make a hissing sound? In this way, they can contrast the behavior of an individual particle of water (or gas) and a macroscopic fluid. One sequence of activities (involving debates, analogies, experiments, and thought experiments) is used to lead students to explain the compressibility of air in terms of a model of vacuum and particles. Another sequence is designed to help them explain the elasticity of air in terms of the continual and random movement of particles. This model in turn helps them to understand air pressure and the diffusion of gases. Thus, central to building an understanding of the atomic-molecular theory is engaging students in cycles of model building while developing their appreciation of the deeper metaphysical and epistemological commitments of atomic-molecular theory. A 3-year longitudinal study showed the much greater effectiveness of this curricular approach in helping students internalize and use the atomic-molecular theory than more traditional didactic instruction (Margel, Eylon, and Scherzo, 2006). Still other phenomena that have been effectively used to initiate discussions of the particulate nature of matter with middle school students concern

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Taking Science to School: Learning and Teaching Science in Grades K-8 explaining the different properties of solids, liquids, and gases (Driver et al., 1995; Lee et al., 1993); thermal expansion of solids, liquids, or gases (Snir, Smith, and Raz, 2003; Lee et al., 1993); changes of state (Lee et al., 1993); dissolving (Lee et al., 1993); the transmission of smells (Nussbaum, 1998); and why materials cannot (chemically) combine in any proportion (Snir, Smith, and Raz, 2003). Based on the findings of this research, the learning progression proposes that during this age band, students can be meaningfully introduced to the following core tenets of atomic molecular theory: Existence of discretely space particles (atoms). There are empty spaces between atoms (idea of vacuum). Each atom takes up space, has mass, and is in constant motion. The existence of over 100 different kinds of atoms; each kind has distinctive properties including its mass and the way it combines with other atoms or molecules. Atoms can be joined (in different proportions) to form molecules or networks—a process that involves forming chemical bonds between atoms. Molecules have different characteristic properties from the atoms of which they are composed. The learning progression also proposes that students should practice using these tenets in cycles of building, testing, and revising models of a wide range of particular situations. This same body of research indicates that it takes considerable time and effort to introduce students to these tenets in a meaningful manner. For example, Nussbaum’s teaching units on the behavior of gases involved over 30 (45-minute) lessons; Lee et al.’s teaching for a broad range of phenomena spanned 10 weeks of sixth grade. However, it may be important to take that time at the middle school level for several reasons. First, understanding the atomic-molecular theory opens up many productive new avenues of investigation about matter. For example, it opens up the whole topic of chemical change, which research suggests is not really accessible to students with only macroscopic criteria for identifying substances (Johnson, 2002). It also helps students much more clearly understand what stays the same and what changes in the water cycle (Lee et al., 1993). Second, many important topics that are discussed elsewhere in the science curriculum, including biology and earth science, depend on these understandings: topics like osmosis and diffusion, photosynthesis, digestion, decay, ecological matter cycling, the water cycle, and the rock cycle, to name just a few. Finally, it provides an opportunity for students to begin to develop an understanding of and respect for the tremendous intellectual work and experimentation that underlies developing a well-tested, successful scientific theory.

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Taking Science to School: Learning and Teaching Science in Grades K-8 How This Contrasts with Current Practice Current texts often have separate chapters for “Properties of Matter,” “Changes in Matter,” and “Atomic-Molecular Theory.” Atomic-molecular theory is often presented as a set of facts (declarative knowledge) about atoms and molecules, disconnected from any concrete everyday experiences that it may help explain. There is often no attempt made to acknowledge the counterintuitive nature of the claims or to show the usefulness of the theory. As a result, as research on student misconceptions makes abundantly clear, the majority of students fail to internalize the core assumptions of the theory, and they have little understanding of such important ideas as chemical change (see Driver et al., 1995, for reviews). As Schwab and others have argued, science is typically taught as “rhetoric conclusions” rather than as a complex process for making sense of the world (in the words of Niels Bohr, a way of “extending our experience and reducing it to order”) that rests on certain metaphysical and epistemological assumptions. Because of this, students do not appreciate what a tremendous intellectual construction a scientific theory really is, why it deserves great respect, and why it cannot be challenged by another idea that does not attempt to meet those epistemological standards. In an important sense, without constructing an understanding of those epistemological standards, students will not know the grounds on which they should believe important scientific theories. In contrast, the proposed learning progression outlines a set of conceptual goals that can be investigated in a more sustained, mutually reinforcing manner, based on a principled interpretation of research on children’s interpretations of matter and materials. In particular, we note that the research enables one to identify phenomena and topics for discussion that will help students make progress with respect to each of the first three strands of scientific proficiency: Understanding and using scientific explanations of the natural world. The learning progression develops atomic-molecular theory as a useful set of conceptual tools that resolve a wide variety of puzzles concerning properties of matter and changes in matter. Description at this level can explain conservation of matter and weight, the composition of materials (elements, compounds), the appearance and disappearance of specific materials, the constancy of materials across change of state, etc. These puzzles are real puzzles for children only if they already have a robust macroscopic understanding of matter and its measured properties. Furthermore, students must master several basic tenets of atomic-molecular theory and use them successfully before the power of atomic-molecular models is apparent.

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Taking Science to School: Learning and Teaching Science in Grades K-8 Generating and evaluating scientific evidence and explanations. The arguments from evidence that support atomic-molecular theory depend on children’s abilities to measure such properties of matter as mass and volume consistently and accurately, as well as their commitment to ideas about the nature of these properties (for example, that mass/weight is a reliable indicator of the amount of matter). Furthermore, they must use these measurements in the context of arguments that require a commitment to logical consistency in predictions and explanations and that involve the coordinated use of model-based reasoning, analogies, and thought experiments. Understanding how personal and scientific knowledge are constructed. In developing an understanding of the atomic-molecular theory of matter, students need to appreciate that the epistemological standards that are central to science and that are used in deciding between competing views (e.g., explanatory scope, rigor, and precision, ability to integrate large patterns of data, generativity of new testable predictions) are actually different from those typically used in everyday life (e.g., consistency with immediate perceptual experience or initial intuitive ideas—standards less dependent on long chains of reasoning and that have a closer match with surface reality or appearance). Thus, mature scientific theories will often embrace core tenets that on the surface seem implausible or even unintelligible to the novice as long as these assumptions are needed to explain a large pattern of data, are supported by a logical chain of reasoning, and can provide detailed explanations of why surface appearances are misleading. The atomic-molecular theory is a clear case in point. The reason scientists believe in the existence of discrete tiny particles in different arrangements and constant motion (i.e., atoms and molecules) is not because of simple, direct perceptual evidence for such a theoretical analysis; rather it is because of the theory’s tremendous explanatory power and scope and detailed experimental support. Thus the strands of scientific proficiency can be used in conjunction with the research to develop understandings in middle school students that build on their learning in elementary school and that lay the foundations for reasoning about matter using atomic-molecular models in many different contexts in the life, earth, and physical sciences. With appropriate preparation and teaching, students can engage in true model-based scientific reasoning. They can come to appreciate both the power of scientific models to predict and explain a diversity of phenomena, and how those models are grounded in careful collection and evaluation of scientific evidence.

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Taking Science to School: Learning and Teaching Science in Grades K-8 Limitations The proposed learning progression is in several ways incomplete or speculative. Limitations stem from the fact that this is a relatively new way of thinking about organizing learning experiences, from questions that have not been examined in research, and from the kind of research available to us. In our extended example at grades 6-8, we assume some instructional history with understanding force and motion that would feed into constructing some elements of the atomic-molecular theory. Yet the nature of that earlier work is not specified. In addition, some prior introduction to ideas about energy, its role in change, and discussion of heat would be important but, again, is not explicitly treated. The case of energy is interesting, because it points to a need for key ideas to be introduced, but perhaps not explicitly defined as they serve as important placeholder ideas. Another issue that was not addressed, in part due to the limited research base, is whether it would be productive to have earlier exploration of the formation and separation of mixtures. Thus, the heavy dependence of this learning progression on ideas about material, matter, weight, volume, density, atom, and molecule should by no means imply that these are the only important notions to be addressed. They are a subset of ideas that are important, and they exist within a broader array of ideas that are not merely related linearly, but also within a web interconnecting learning among multiple learning progressions. The research base itself also necessarily limits the quality of our conceptualization of learning progressions. We have relied on many short-term studies and assembled these in an effort to depict learning across longer periods of time. Furthermore, these studies are primarily studies of knowledge—snapshots of students’ capabilities at a given time—not depictions of learning or the change in capability over time. While our learning progression highlights the ways in which one could be doing more in elementary school to provide a productive foundation for later learning, there is little research to guide in identifying key early experiences. What are the ideas and practices that, if learned early on, would provide greater cognitive payoffs down the road? CONCLUSIONS We can see implications of learning progressions like the one described above for several areas of policy and practice, including curriculum and standards, assessment, and classroom instruction. Curriculum and standards. This learning progression suggests several ways in which current curricula and standards are problematic and

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Taking Science to School: Learning and Teaching Science in Grades K-8 could be improved. This learning progression suggests ways in which students of different ages could learn age-appropriate versions of core ideas with understanding, rather than addressing them in current haphazard ways. This learning progression also suggests priorities in the curriculum, helping to identify the conceptual tools and practices that are the foundation for critical learning. Suggesting appropriate ages for introduction of key ideas. For example, many textbooks and state curricula introduce atomic-molecular stories (not functional as models) as early as third or fourth grade, while the national science education standards delay atomic-molecular models until high school. This research suggests why middle school students could benefit from learning to use atomic-molecular models and what the key elements of those models might be. Large-scale and classroom assessment. This learning progression suggests the most important conceptual tools and practices to be assessed, common alternatives or misconceptions, and specific questions or tasks that could be used (for an extensive discussion of assessment in the learning progressions framework, see Smith et al., 2006). Classroom instruction. What is known about mechanisms of learning can be useful for guiding classroom instructions: key questions to address with children of different ages, important experiences that may move the process of succession forward, and key conceptual tools and practices that can be introduced and mastered. Taken together, these literatures (on preschool understanding, mature scientific understanding, the response of children to sustained good instruction) along with societal expectations and values could form a powerful set of constraints on the development of a set of plausible learning progressions. Clearly, though, there could be more than one way to make choices about what core ideas should be the focus for learning progression analysis. Undertaking the intellectual task of thinking through detailed learning progressions for different end-state core ideas, however, might be one step in thinking through possible advantages and disadvantages of different approaches. In addition, even if we agree on focal core ideas that are the target of instruction and a learning progression that connects the two end points, it would not fully prescribe the instructional sequence. In much the same way as there are constraints on how a complex structure such as a house can be built from its starting components—for example, certain things such as the foundation and then walls must come first to provide structural support for the windows and roof—yet within those constraints there is some flexibility as well and multiple ways to build a house.

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Taking Science to School: Learning and Teaching Science in Grades K-8 REFERENCES American Association for the Advancement of Science. (1993). Benchmarks for science literacy. New York: Oxford University Press. American Association for the Advancement of Science. (2001). Atlas of science literacy: Mapping K-12 learning goals. Washington, DC: Author. Baroody, A.J., Cibulskis, M., Lai, M-l, and Li, X. (2004). Comments on the use of learning trajectories in curriculum development and research. Mathematical Thinking and Learning, 6(2), 227-260. Carey, S. (1991). Knowledge acquisition: Enrichment or conceptual change? In S. Carey and R. Gelman (Eds.), The epigenesist of mind: Essays on biology and cognition (pp. 257-291). Hillsdale, NJ: Lawrence Erlbaum Associates. Dickinson, D.K. (1987). The development of material kind. Science Education, 71, 615-628. Driver, R., Leach, J., Millar, R., and Scott, P. (1995). Young people’s images of science. Buckingham, England: Open University Press. Johnson, P. (1996). What is a substance? Education in Chemistry, March, 41-45. Johnson, P. (2002). Children’s understanding of substances, part 2: Explaining chemical change. International Journal of Science Education, 24(10), 1037-1054. Kesidou, S., and Roseman, J.E. (2002). How well do middle school science programs measure up? Findings from Project 2061’s curriculum review. Journal of Research in Science Teaching, 39(6), 522-549. Krnel, D., Glazar, S.A., and Watson, R. (2003). The development of the concept of “matter”: A cross-age study of how children classify materials. Science Education, 87, 621-639. Krnel, D., Watson, R., and Glazar, S.A. (1998). Survey of research related to the development of the concept of “matter.” International Journal of Science Education, 20(3), 257-289. Lee, O., Eichinger, D.C., Anderson, C.W., Berkheimer, G.D., and Blakeslee, T.D. (1993). Changing middle school students’ conceptions of matter and molecules. Journal of Research in Science Teaching, 30(3), 249-270. Lehrer, R., Catley, K., and Reiser, B. (2004). Tracing a prospective learning progression for developing understanding of evolution. Commissioned paper for the National Research Council Committee on Test Design for K-12 Science Achievement Workshop, May 6-7, Washington, DC. Available: http://www7.nationalacademies.org/bota/Evolution.pdf [accessed November 2006]. Lehrer, R., Jaslow, K., and Curtis, C. (2003). Developing understanding of measurement in the elementary grades. In D.H. Clements and G. Bright (Eds.), Learning and teaching measurement. 2003 yearbook (pp. 100-121). Reston, VA: National Council of Teachers of Mathematics. Lehrer, R., Jenkins, M., and Osana, H. (1998). Longitudinal study of children’s reasoning about space and geometry. In R. Lehrer and D. Chazan (Eds.), Designing learning environments for developing understanding of geometry and space (pp. 137-167). Mahwah, NJ: Lawrence Erlbaum Associates. Lehrer, R., and Schauble, L. (2000). Modeling in mathematics and science. In R. Glaser (Ed.), Advances in instructional psychology: Educational design and cognitive science (vol. 5, pp. 101-159). Mahwah, NJ: Lawrence Erlbaum Associates.

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Taking Science to School: Learning and Teaching Science in Grades K-8 Lehrer, R., Schauble, L., Strom, D. and Pligge, M. (2001). Similarity of form and substance: Modeling material kind. In S. Carver and D. Klahr (Eds.), Cognition and instruction: Twenty-five years in progress. Mahwah, NJ: Lawrence Erlbaum Associates. Margel, H., Eylon, B.S., and Scherz, Z. (2006). We actually saw atoms with our own eyes: Conceptions and convictions is using the scanning tunneling microscope in junior high school. Journal of Chemical Education, 81(4), 558-566. Metz, K.E. (1993). Preschoolers’ developing knowledge of the pan balance: From new representation to transformed problem solving. Cognition and Instruction, 11, 31-93. Metz, K.E. (1995). Reassessment of developmental constraints on children’s science instruction. Review of Educational Research, 65, 93-127. Mintzes, J.J., Wandersee, J.H., and Novak, J.D. (1997). Meaningful learning in science: The human constructivist perspective. In G.D. Phye (Ed.), Handbook of academic learning (pp. 405-447). San Diego, CA: Academic Press. National Research Council. (1996). National science education standards. National Committee on Science Education Standards and Assessment. Washington, DC: National Academy Press. Nussbaum, J. (1998). History and philosophy of science and the preparation for constructivist teaching: The case for particle theory. In J.J. Mintzes, J.H. Wandersee, and J.D. Novak (Eds.), Teaching science for understanding (pp. 165-194). New York: Academic Press. Piaget, J., and Inhelder, B. (1974). The child’s construction of physical quantities. London, England: Routledge and Kegan Paul. Roseman, J.E., Kesidou, S., Stern, L., and Caldwell, A. (1999 November/December). Heavy books light on learning: AAAS Project 2061 evaluates middle grades science textbooks. Science Books & Films, 35(6), 243-247. Roth, K.J. (2002). Talking to understand science. In J. Brophy (Ed.), Social constructivist teaching: Affordances and constraints (Advances in Research on Teaching, vol. 9, pp. 197-262). New York: JAI Press. Schmidt, W., Wang, H.C., and McKnight, C. (2005). Curriculum coherence: An examination of U.S. mathematics and science content standards from an international perspective. Journal of Curriculum Studies, 37, 525-559. Smith, C. (2005). Bootstrapping processes in the development of students’ commonsense matter theories: The role of analogical mapping, though experiments, and learning to measure. Submitted to Cognitive Psychology. Smith, C., Carey, S., and Wiser, M. (1985). On differentiation: A case study of the development of the concepts of size, weight, and density. Cognition, 21, 177-237. Smith, C., Maclin, D., Grosslight, L., and Davis, H. (1997). Teaching for understanding: A study of students’ preinstruction theories of matter and a comparison of the effectiveness of two approaches to teaching students about matter and density. Cognition and Instruction, 15, 317-393. Smith, C., Snir, J., and Grosslight, L. (1992). Using conceptual models to facilitate conceptual change: The case of weight/density differentiation. Cognition and Instruction, 9(3), 221-283.

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Taking Science to School: Learning and Teaching Science in Grades K-8 Smith, C.L., Solomon, G.E.A., and Carey, S. (2005). Never getting to zero: Elementary school students’ understanding of the infinite divisibility of number and matter. Cognitive Psychology, 51(2), 101-140. Smith, C., Wiser, M., Anderson, C.A., and Krajick, J. (2006). Implications of research on children’s learning for standards and assessment: A proposed learning progression for matter and atomic molecular theory. Measurement: Interdisciplinary Research and Perspectives, 4. Smith, C., Wiser, M., Anderson, C.A., Krajick, J., and Coppola, B. (2004). Implications of research on children’s learning for assessment: Matter and atomic molecular theory. Commissioned paper for the National Research Council Committee on Test Design for K-12 Science Achievement Workshop, May 6-7, Washington, DC. Available: http://www7.nationalacademies.org/bota/Big%20Idea%20Team_%20AMT.pdf [accessed November 2006]. Snir, J., Smith, C.L., and Raz, G. (2003). Linking phenomena with competing underlying models: A software tool for introducing students to the particulate model of matter. Science Education, 87, 794-830. Stavy, E. (1991). Children’s ideas about matter. School Science and Curriculum, 91, 240-244. Valverde, G.A., and Schmidt, W.H. (1997). Refocusing U.S. math and science education. Issues in Science and Technology, 14(2), 60-66. Wilkening, F., and Huber, S. (2002). Children’s intuitive physics. In U. Goswami (Ed.), Blackwell handbook of childhood cognitive development (pp. 349-370). Malden, MA: Blackwell. Yair, Y., and Yair, Y. (2004). Everything comes to an end: An intuitive rule in physics and mathematics. Science Education, 88(4), 594-609.