The Lawrence Hall of Science will be launching with this grant a three year dissemination effort designed to bring Great Explorations in Math and Science (GEMS), an activity-based science curriculum, into elementary and middle school classrooms nationwide, and to help determine the effectiveness of such a dissemination model. GEMS is a series of thirty teacher's guides to activities that are exciting and fun yet meet the content and process objectives of school-based science. GEMS activities have been extensively tested and improved by classroom teachers. They can be used to supplement or replace existing curricula, and require only easily accessible materials. Dissemination will be through orientation workshops to 2000 individual teachers and teacher educators across the nation who already implement activity-based materials in the classrooms or who are interested in improving the teaching of elementary school science.