The development of children's causal knowledge is investigated by analyzing changes in the content and form of the explanations they generate across the age span of three to nine years. The balance of incremental versus fundamental change and the forms each takes in children coming to understand the working of gears are examined. Three phases of…

Reports on a study which investigated the order of acquisition of intuitive notions of qualitative speed. Results indicated that an array of prerequisites, equivalent, and independent relationships existed among the tasks administered. Confirmed the evolution of reasoning for notions of qualitative speed found by Piaget. (Author/TW)