living kinds. Finally, the idea that biological entities are embedded in rich and deep taxonomies may not be strictly true for only living things, but when used with the essentialist bias and teleological interpretations, it helps to further demarcate the set of living things. Moreover, there are strong cross-cultural universals in the use of folk biological taxonomies, suggesting a way of organizing the living world that remains robust across both culture and development (Lopez et al., 1997).

The use of a teleological or “design” stance to understand living things is particularly interesting. When children are asked to explicitly reject or accept whether functional attributions can be made about nonliving natural kinds, such as rocks, preschoolers tend to give a functional attribution (Kelemen, 1999). Yet the ability to make explicit judgments about whether a teleological explanation is applicable may emerge later. Young children may in fact have a more tacit understanding that is revealed in their spontaneous use of such explanations in attempts to learn more about the biological and physical worlds. For example, when preschoolers are shown novel artifacts and living things, their spontaneous questions about them reveal sharply contrasting patterns for artifacts and living things. They tend to ask more questions about the purposes of whole artifacts and about the parts of animals rather than about the purposes of whole animals (Greif et al., 2006). Thus, when children later enter a more formal setting of science education, their competence may be underestimated if they are assessed in terms of their judgments of the appropriateness of certain forms of explanation for certain phenomena. Greater competence may be revealed by looking at their spontaneous use of questions.

Overall, well before elementary school begins, children are sensitive to a variety of high-level causal and relational patterns that are particularly useful for reasoning about living things. The most dramatic cases of cognitive change seem to involve learning about more detailed mechanisms of biological systems, much of this occurring during the elementary school years. In addition, an explicit awareness of plants and animals as a distinct domain governed by unique sets of mechanistic principles may undergo considerable development during childhood; it may change from a simple notion of seeing plants and animals as special because of a vital force to seeing them as engaging in unique metabolic activities (Inagaki and Hatano, 2002, 2006).

Substances and Their Transformations

As adults, people think of chemistry as the study of the composition of matter and changes that it can undergo, both in isolation and in combination with other forms of matter. There is a great deal of knowledge involved in mature scientific notions of chemistry, ranging from atomic theory, to mecha-

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