Proposes a theoretical model of cognitive development and applies this model to the secondary analysis of two large-scale studies which focus on the acquisition of formal operational schemata by adolescents in the United States and Israel. Results support the "unity" hypothesis of cognitive development that the various schemata of formal…

A nonequivalent control group design study, with a math unit on ratio and proportion as the treatment, was conducted to examine the validity of some written tasks as a measure of formal reasoning. Subjects in the study were 68 fifth grade students who enrolled in two classes in a small urban school. The experimental group learned a 12-lesson math…

Investigated were gender-related differences in the relationship between the development of formal reasoning skills and learning interests during the early adolescent stage. Results indicated that adolescent boys appeared to develop patterns of formal reasoning before their female classmates. Differences in subject preferences were also found. (CW)