ingly competent and able to engage in learning across all four strands of scientific proficiency from the very beginning of their science education.
We begin with a discussion of young children’s knowledge of the natural world. This knowledge can emerge as a consequence of a child’s everyday interactions with the world as well as a result of the ways in which the culture and its adult members explicitly impart information to children. In some areas of instruction, such as reading, the role of preexisting knowledge and understanding may be relatively modest, but in the area of science education, children bring a great deal that is relevant. A major challenge is to build on students’ existing knowledge of the natural world to help them understand and use scientific knowledge.
Next we identify aspects of young children’s thinking that can serve as the foundation for developing scientific reasoning in the elementary grades. For example, young children understand that one thing can represent another (such as a toy airplane or a scale model), which provides a starting point for modeling. Finally, we consider precursors to children’s understanding of how scientific knowledge is constructed. We include here their understanding of the ideas and beliefs held by other people and their ability to assess the credibility of different sources of knowledge.
Several themes run repeatedly through the research on young children’s emerging understandings of natural systems and their reasoning. The following three themes help organize the research summaries that follow:
Concern with explanation and investigation are central to children’s learning and thinking at all ages. Even the youngest children are sensitive to highly abstract patterns and causal relations. They use this information to guide the ways in which they generalize, make inferences, and make sense of the world. There is increasing recognition of the richness and variability of children’s understandings that involve implicit and explicit, nonsymbolic and symbolic, associative and explanatory components. There is no simple concrete to abstract progression in children’s development.
Children develop explanatory insights in specific domains. Some key domains of understanding may have a privileged status in helping with the emergence of science. These include mechanics, folk biology, some aspects of chemistry (e.g., an initial understanding of different substances), and folk psychology, as explained below. These four domains have universal shared components throughout the world and for children from all backgrounds in the United States. They form an important cognitive common ground on which to build more sophisticated scientific understandings. Roots of these