Examines the relationships between mental maturity and achievement in three types of science concepts-classificational, correlational, and theoretical. (AL)

Defines five levels between concrete and formal operation in the development of the concept of controlling variables. The sample, methodology and research on which the work is based is described in SE 519 500. (CP)

Reported is the production of an instructional methodology harmonizing with Piagetian theory and enabling teenage students, including those initially mismatched to the task, to understand the mole, as revealed by their performances on a test of basic skills considered fundamental to that concept. (DS)