Investigates the effects of two context variables on the performance of seventh-grade students on a qualitative and numerical proportional reasoning test. Explores the nature of the relationships between rational number skills, qualitative reasoning about ratios, and numerical proportional reasoning. (Author/YP)

Investigates whether the formal schemata and propositional logic are acquired gradually across age during adolescence, in agreement with Piaget's logical analysis of the structure of formal thought, or acquired in wholesale spurts, thus disagreeing with Piaget's theory. (GA)

Reports results of a study investigating the ability of college students to solve problems using proportional reasoning. Also discusses implications for consideration of Piagetian cognitive level of students in planning college courses. (CS)

Examines successful/unsuccessful distinctions between novices and experts in problem solving in terms of genetic knowledge, use of production rules, strategy selection, use of critical cues, use of logic, understanding of probability, and the thinking process itself. Suggests five implications for genetics instruction and provides three problems…

Four types of proportionality problems were administered to: (1) secondary school students who were enrolled in Project Physics, and (2) students not enrolled in physics. Both samples were randomly selected. Groups were not found to differ significantly in problem solving ability but both revealed that the ability to solve certain problems was…