This project will develop video, computer, and print materials that will enhance the teaching of geometry in secondary schools. The central medium will be broadcast-quality videotapes, which will consist of computer generated animation accompanied by narration and some text. Workbooks will allow the video materials to be used either for classroom instruction or for independent study. Related computer programs, together with high quality documentation, will also be developed, allowing students to explore geometric concepts interactively. A useful byproduct of the project will be a "geometer's sketch pad", a program that will enable geometers working with inexpensive microcomputers to sketch geometric figures in two and three dimensions and to apply geometric transformations that will permit visualization from different perspectives. This program will be used by the project staff for prototyping animation sequences. It will also be of interest to other mathematicians and will be appropriate as an instructional tool for use with gifted students.