This project is aimed at perfecting and testing a new instructional method to improve the effectiveness of introductory physics teaching. the methods has two chief characteristics: 1) a systematic challenge to common sense misconceptions about the physical world, and 2) an emphasis on models and modeling as basic to physical understanding. Two versions of the method will be tested. The first version is designed especially for high school physics. It emphasizes student development of explicit models to interpret laboratory activities. After an initial test, this version will be taught to high school physics teachers in a summer Teacher Enhancement Workshop, and its effect on their subsequent teaching will be evaluated. Teachers with weak as well as strong backgrounds will be included. A special effort will be made to include females and minorities. The second version will be tested in a special college physics course designed to prepare students with weak backgrounds for a standard calculus based physics course. It emphasizes modeling techniques in problem solving. This project is jointly supported by the Division of Materials development, Research and Informal Science Education and the Division of Teacher Preparation and Enhancement.