This article builds on two previous ones in which we presented the processes of construction and consolidation of one student's knowledge structures about comparisons of infinite sets, according to a recently proposed theory of abstraction. In the present article, we show that under slight variations of context, knowledge structures that have…

Three studies examined the domain of concepts about dinosaurs in order to assess how the domain might be structured in 4- through 7-year-old children's representations and to explore how the knowledge might be used. Findings indicated that significant differences exist in the way expert and novice children's representations are structured.…

Adolescents with mental retardation viewed a story enacted with props and were asked questions about the knowledge and beliefs of the characters. Subjects performed worse than did nondisabled children matched for mental age. Subjects did better on questions requiring first-order reasoning than on those involving second-order reasoning. (Author/JDD)

Discusses children's use of metaphors to create meaning, using as an example the pragmatic and "scientific" ways in which preschool children explain thunder and lightning to themselves. Argues that children are being shortchanged by modern scientific notions of abstractness and that they should be encouraged to create their own explanations of…