This empirical study applies the learning progression perspective to the teaching of evolution, posting an initial progression for the conceptual underpinnings of evolution for second and third graders. The centrality of evolution makes it a prime target for strategic long-term coherent knowledge-building. Two curriculum models?one in animal behavior and one in botany?support the learning progressions. These modules build on the PIs? prior work, scaffolding primary grade children?s scientific inquiry in these domains. The research team studies the curricular enactment and student learning in two kinds of sites, (1) a project-run summer enrichment program, and (2) inner-city public school classrooms.
Developing the Conceptual Underpinnings of Evolution in Second and Third Grade According to the National Research Council’s report, Taking science to school: Learning and teaching science in grades K-8 (Duschl, Schweingruber, & Shouse, 2007), much of elementary science education today is based on the problematic assumption that what children can learn is largely determined by their grade level as a proxy for developmental stage. This view fails to recognize the potential impact of instruction on children’s capabilities, especially instruction that capitalizes on children’s fruitful intuitions and leverages these understandings to systematically build more powerful and coherent knowledge over time. The NRC report concludes, "further research and development is needed to identify and elaborate the progressions of learning and instruction that can support students’ understanding of ... core ideas across the disciplines of science". We conceptualize a "learning progression" as a model of a strategic pathway of emergent understanding of a core disciplinary idea, contingent on a particular, relatively optimal instructional model. In accordance with the report’s recommendations, this research project elaborated a learning progression to develop second and third graders’ understandings of the conceptual underpinnings of evolution. While a learning progression about evolution in the primary grades is only a beginning, it can serve as a productive building block in coming to understand this difficult conceptual terrain. The puzzle of the dynamics of the "fit" between organisms and their environment has long been a big question underlying biology. In the spirit of Jerome Bruner’s (1969) recommendation that educators organize curriculum around a few "lithe, beautiful, and immensely generative" ideas, we frame the learning progression around increasingly powerful explanations of the fit between organisms and their environment. The progression builds toward a rudimentary understanding of natural selection at the system level of microevolution, involving natural selection within a population from one generation to the next (e.g.; decreasing relative frequency of the inherited trait of bright coloration in male guppies from one generation to the next, following arrival of predator fish within a pool). While understanding evolution poses nontrivial challenges at all age levels, the developmental literature reveals that young children have many relevant intuitions on which a learning progression in this conceptual terrain can build (e.g.; rudimentary ideas of life cycle, structure/function, inheritance, chance, and variation.) The final model (See Figure 1) includes two dimensions and a final integration thereof. Dimension 1 (in orange) traces increasingly more adequate explanation of what organisms live where; i.e., the state of the good fit between organisms and their environment. Dimension 2 (in green) traces emergent explanation of the mechanism by which the fit develops, i.e. how organisms become well-adapted to where they live. We developed a powerful pedagogical model to develop these ideas. Five principles define the model: 1. Understanding a scientific concept entails using the concept in the practices of science, including interpretation of the natural world, making predictions, and developing explanations. 2. Build children’s conceptual understanding in the context of their engagement in scientific knowledge-building practices, including field- and laboratory-based empirical inquiry, text-based research, and thought experiments. 3. Leverage strategically selected in-depth cases as a basis to build generalizations and abstractions. 4. Immerse children in exploration of the phenomenology of the case and the puzzling patterns therein prior to introducing the corresponding explanatory abstraction. 5. Emphasize the metacognitive knowledge that supports children’s understanding of the power of the targeted ideas in explaining the fit between organisms and their environment. The team developed two curriculum modules (in botany and animal behavior) that supported children’s emergent understanding of these ideas in accordance with the pedagogical model. Second and third grade teachers, in both research team taught summer school and regular school-year classrooms implemented the curriculum. Both sites served children from largely low income, ethnic minority populations. Over two years of implementation in the two sites, about a third of the children participated in both curriculum modules, revisiting the challenging conceptual terrain in a second domain. Despite well-documented challenges to understanding natural selection, this research found that second and third graders can make solid progress in coming to understand the mechanism of natural selection at the system level of microevolution (as reflected in gains in individuals’ composite scores from pre- to post-test interviews). In contradiction to widely shared assumptions about developmental constraints on primary grade children’s thinking, these second and third graders were able to develop an understanding of abstract ideas with explanatory power and to appropriately apply these ideas in the interpretation and explanation of relevant biological phenomena. This research suggests there is considerable plasticity in young children’s capabilities to understand abstract scientific ideas, under relatively optimal instructional conditions. Furthermore, the learning progressions approach of strategically leveraging young children’s productive intellectual resources in systematically building toward more powerful understanding appears key to revealing children’s emergent conceptual power and reforming science education.
