The design and architecture of two user-controlled, computer-based problem analysis environments in classical mechanics are discussed. In the expert-like environment, the user analyzes problems according to a hierarchical concept schema consistent with how experts analyze novel problems in physics. In the second environment, the user searches a data-base of equations using novice-like, surface feature keywords in order to locate the appropriate equation(s) to use in solving a problem. Cognitive and pedagogical implications of the research are discussed. (Author)