The paper critically appraises the concept-learning and developmental perspectives in science education to show that Pascual-Leone's Theory of Constructive Operators leads to a progressive problem-shift between Piaget's epistemic subject and Pascual-Leone's metasubject. (SM)

In an attempt to specify in some canonical terms what many heuristic programs known as "expert systems" do, an analysis was made of ten rule-based systems. It was found that these programs proceed through easily identifiable phases of data abstraction, heuristic mapping onto a hierarchy of pre-enumerated solutions, and refinement within this…