of data (Strand 2) becomes evidence that they use to reflect on and reason with (Strand 3). That, in turn, prompts them to ask more questions and search for information from a number of different sources, which leads them to a deeper understanding of the biological processes at work (Strand 1). As their understanding of biological explanations increases, their questions and their search for evidence grow more complex and focused (Strand 2). For example, as the students come to understand the relationship between food sources and population density, they seek out better techniques for mapping populations and population density in different parts of the yard. They seek out more sophisticated tools for mapping and graphing the density of certain plants and measuring the height of woody plants (Strand 2).

As the sophistication of their tools increases, their evidence grows richer and their techniques more systematic (Strand 2). This also leads to more disagreements about measurements and more discussions about the quality and reliability of data (Strand 3). Over time, the students’ reasoning about and understanding of trends and patterns grows more sophisticated (Strand 1) and their questions evolve further. They have more critical discussions about trade-offs among different methods of data collection and the fruitfulness of particular lines of investigation (Strands 3 and 4). As their questions grow more complex and their understanding of what counts as evidence grows more sophisticated, the design of their investigations becomes more nuanced and appropriate (Strands 1, 2, 3, and 4).

The techniques that Mr. Walker and Ms. Rivera used to promote cross-talk and whole-group discussion allowed everyone to have access to the thinking, data, and discoveries of others (Strand 4). At monthly biodiversity conferences, they were able to critique one another’s proposals and designs with counterevidence and make constructive suggestions based on previous efforts (Strands 3 and 4).



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