practice (see Lehrer and Schauble, 2006). The science-as-practice perspective invokes the notion that learning science involves learning a system of interconnected ways of thinking in a social context to accomplish the goal of working with and understanding scientific ideas. This perspective stresses how conceptual understanding of natural systems is linked to the ability to develop explanations of phenomena and to carry out empirical investigations in order to develop or evaluate knowledge claims.
The strands framework emerged through the committee’s syntheses of disparate research literatures on learning and teaching science, which define science outcomes differently and frequently do not inform one another. The framework offers a new perspective on what is learned when students learn science. First, the strands emphasize the idea of knowledge in use. That is, students’ knowledge is not static, and proficiency involves deploying knowledge and skills across all four strands in order to engage successfully in scientific practices. The content of each strand described below is drawn from research and differs from many typical presentations of goals for science learning. For example, we include an emphasis on theory building and modeling, which is often missing in existing standards and curricular frameworks. And, the fourth strand is often completely overlooked, but research indicates it is a critical component of science learning, particularly for students from populations that are typically underrepresented in science.
These strands illustrate the importance of moving beyond a simple dichotomy of instruction in terms of science as content or science as process. That is, teaching content alone is not likely to lead to proficiency in science, nor is engaging in inquiry experiences devoid of meaningful science content. Rather, students across grades K-8 are more likely to advance in their understanding of science when classrooms provide learning opportunities that attend to all four strands.
Knowing, using, and interpreting scientific explanations encompasses learning the facts, concepts, principles, laws, theories, and models of science. As the National Science Education Standards state (National Research Council, 1996, p. 23):
Understanding science requires that an individual integrate a complex structure of many types of knowledge, including the ideas of science, relationships between ideas, reasons for these relationships, ways to use the ideas to explain and predict other natural phenomena, and ways to apply them to many events.
Understanding natural systems requires knowledge of conceptually central ideas and facts integrated in well-structured knowledge systems, that is, facts