NSES and benchmarks recognize the importance of the first three strands of science learning, each strand is described separately, so the crucial issue of how the strands are interwoven and how they support each other is not addressed.
Although there is a solid research base that supports the premises of organizing science around core concepts, one should be mindful that few studies have examined children’s learning of core concepts over multiple years. So questions about what the optimal set of core concepts are, how they should be distributed and organized over the grades, and how to link together instruction across the grades are as yet unanswered. It is, however, very clear that future revisions to the national science standards—and the subsequent interpretation of those standards at the state and local levels and by curriculum developers—should dramatically reduce the number of topics of study and provide clear explanations of the knowledge and practices that can be developed from kindergarten through eighth grade.
Research indicates that one of the best ways for students to learn the core concepts of science is to learn successively more sophisticated ways of thinking about these ideas over multiple years. These are known as “learning progressions.” Learning progressions can extend all the way from preschool to twelfth grade and beyond—indeed, people can continue learning about core science concepts their whole lives. If mastery of a core concept in science is the ultimate educational destination, learning progressions are the routes that can be taken to reach that destination.
Learning progressions for K-8 science are anchored at one end by the concepts and reasoning abilities that young children bring with them to school and at the other end by what eighth graders are expected to know about science. The most effective and appropriate concepts on which to build learning progressions are those that are central to a discipline of science, that are accessible to students in some form starting in kindergarten, and that have potential for sustained exploration across grades K-8. A well-designed learning progression will include the essential underlying ideas and principles necessary to understand a core science concept. Because learning progressions extend over multiple years, they prompt educators to think about how topics are presented at each grade level so that they build on and support each other.