Discusses the possibilities of accelerating the rate of cognitive development and describes the design and trial of intervention lessons. Gives preliminary results from one laboratory school indicating that the possibility of accelerating general cognitive development is worth pursuing. (YP)

Examines whether participation in physical experiments together with social interaction with adults and school-mates favor the development of causal knowledge and the understanding of a complex physical subject. Concludes that the treatments can lead students to give up pre-causal explanations and to resort to physical ones. (Author/YP)