Investigated were children's reactions when allowed to choose their own apparatus and perform experiments with appropriate directions available. Few students invented their own experiments; most followed the available printed instructions. (SL)

Described is a study that confirms positive effects on student achievement of manipulation of molecular models by high school chemistry students over a long period of time. Also examined but unanswered were questions regarding applications of Piaget's theories in determining differential effects for concrete and formal operational students. (CS)