A major theme across the chapters is how findings from research have increasingly revealed interconnections between the four strands as children develop scientific understanding at all grade levels. The evidence is especially strong that knowledge of the natural world (Strand 1, Chapter 4) and the ability to generate and evaluate evidence and explanations (Strand 2, Chapter 5) are closely intertwined. Work on the connections between Strands 1 and 2 and Strand 3—understanding the nature and development of scientific knowledge (Chapter 6)—is more recent. However, this connection has strong theoretical support, and emergent empirical work documenting the links is compelling. Connections between Strand 4 (Chapter 7), productive participation in science, and the other three strands have less direct empirical support in science. However, work in other subject areas, such as mathematics and reading, supports the idea that there is a connection and that the connection depends on incorporating certain science practices, like modeling, and discourse practices, like argumentation, into science learning environments.
Another major theme across Part II is the strong evidence from current research that children are more capable than was once thought and that implementation of the strands framework could begin as early as kindergarten. In fact, basic research in cognitive development over the past few decades has revolutionized the view of how children’s minds develop, from infancy through adolescence. It turns out that children come to school with a great capacity for learning in general as well as for science learning, and they are able to engage in surprisingly sophisticated scientific thinking in the early grades.
Finally, across the four chapters we review research on how science reasoning and the growth of scientific knowledge develops in the elementary and middle school grades. The research reveals surprisingly diverse capabilities within a given age group as well as variation within a single individual depending on the nature of the task, problem, or inquiry at hand.