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…

Performance on five logical, spatial, and formal tasks was used to make inferences about the reasoning structures of 101 middle and high school students. Findings (obtained during interviews) include grade level differences in performance and sex differences in performance on one of the tasks. Implications for instruction are proposed. (Author/JN)

Describes a study that explores the instructional influence of presenting pictures at the molecular level when introducing chemistry concepts and solving chemistry problems. Explores the effect of the pictures on students' conceptions and problem-solving abilities. Contains 59 references. (DDR)