The target of difficulty of the Educational Technology Center (ETC) Heat and Temperature Group is basic thermal physics, particularly the differentiation between heat and temperature. High school teachers often find that thermal concepts are very difficult for their students to master and attribute students' difficulties at least in part to the failure to differentiate between heat and temperature. This failure would indeed account for the students' poor learning, since most thermal variables, laws, and principles are based on the differentiation and relation between heat and temperature. This group's curriculum has used microcomputers as laboratory tools: Microcomputer-Based Laboratories (MBL) allow students to collect, display, and summarize data collected from the "real world," while with Computer Laboratory Simulations students watch "ideal" experiments on the screen, setting parameters, not collecting data. Classroom interventions have helped students at the problem-solving level: students taught with microcomputers were better than control students at solving quantitative problems of the type given in science tests, but no evidence was found that the computer-based curriculum facilitated conceptual change. This report summarizes past work and the development of computer conceptual models, and reports the results of a pilot study conducted to test the models. (CW)