Reviews the individualized format of the Keller Plan and an audiotutorial approach. Outlines differences in student thinking strategies and explores the implications of these differences in the realms of teaching strategies and questioning techniques. Advocates improvement in assessing when each learner is ready for which content. (GS)

Studies of the hierarchical attainment of conservation of physics concepts revealed significant differences with respect to age, sex, and grade level in a random sample of seventh and eighth grade students. Conservation of a quantity did not necessarily depend on the prior conservation of its constituent fundamental quantities. (MLH)

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)