A broad literature review revealed that younger children are more likely to categorize objects along complimentary dimensions than older children who tend to categorize according to similarity. This developmental change is discussed in terms of etiology--internal organismic changes or environmental changes. (DP)

Explores age differences in children's conceptions of play, pretending, and toys. Examines parallel structural changes in other areas of development, such as language acquisition. Subjects for the study were 5-, 7-, 9-, and 11-year-old children. (BD)

Outlines Piaget's late ideas on categories and morphisms and the impact of these ideas on the comprehension of the inclusion relationship and the solution of arithmetic problems. Reports a study in which fourth through sixth graders were given arithmetic problems involving two known quantities associated with changes rather than states. Identified…

Investigates the effect of various strategy-modeling techniques on the performance of both young children and elderly adults on the 20 Question Task. (Author/MP)

Examination of the way in which children conceive the development of animals shows that there are parallels among concepts of development with those of the periods of concrete operations and formal operations. The conception of development seems to advance further in the subsequent period of dialectical thought. (MS)