Empirical data relate to Bruner's and Ausubel's theories of learning concepts at different age levels. The concept of vector addition was taught to eighth, ninth, and tenth grade students. The concept was learned and retained by high ability ninth and all tenth grade students. (PS)

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)