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 study (n=631) of children's ideas on motion of objects is reported. On three items of a four-part questionnaire, responses changed as the children matured, passing through distinct, successive stages with respect to their conceptual understanding. If teaching strategies to overcome misconceptions are to be effective, they must be appropriate to…