The purpose of this project is to demonstrate the feasibility of redesigning courses in mathematics and science by incorporating into the courses research results from cognitive science, and by focusing on the development of pedagogical content knowledge. The three courses selected, one-semester courses in biology, calculus. and rational number learning and probability, are all courses in a program for preparing middle school teachers of mathematics and science. The project would begin with a preparatory faculty seminar covering research on topics such as organization, memory constraints, analogical reasoning, and semantic networks. Pairs of Faculty would plan each course in the fall term, and team-teach it in the spring term. understanding of content will be evaluated by content specialists and cognitive psychologists with written examinations, individual interviews, and a computer-based semantic network program. If successful, the project will form the basis for planning a new teacher preparation program for middle school teachers of mathematics and science.