When teachers possess detailed knowledge about children's thinking and problem solving, it can profoundly affect their knowledge of their students and their planning for instruction. Reported is a project designed to demonstrate the feasibility of redesigning courses for prospective teachers in mathematics and science by incorporating into the courses research results from cognitive science and by focusing on the development of pedagogical content knowledge. After the background of the project is presented, the section on the project's implementation describes the preparation stages and the three courses offered in four sections. Section 1: Cognitive Seminar for Teacher Preparation Project, describes the organization of knowledge, how it will be presented in the classroom, and how student learning and attitudes towards learning will be assessed for the three courses being designed. Section 2 describes the mathematics course entitled "Calculus for Middle School Teachers," including course development activities, evaluation data, and implications for curriculum development. Section 3 describes the mathematics course entitled "Mathematics Course for Elementary/Middle School Teachers: Rational Numbers, Proportional Reasoning, Probability, Statistics," including course planning, instruction, information about students, evaluation of student affect and knowledge measures, and a discussion of instructor impressions of students. Section 4 describes the biology course entitled "Process and Inquiry in Life Science," including an overview of the course, the materials and methods used during teaching, results of science process skills and affective attitudes of experimental and comparison groups, and discussion and conclusions from the results. Appendices including pertinent documents with respect to activities used in lessons taught, evaluation instruments for knowledge and attitude measures, data gathered in the study, and reports made at the Psychology of Mathematics Education are given. (MDH)