This 3-year project is designed to enhance the physical science knowledge base of 4-9 teachers in South Carolina. The plan is to develop science teacher leaders by using master science teachers for instruction and mentoring. The target population will consist of teams of lead teachers from the same school and school district in order to strengthen communication and cooperation for the improvement of science education. This proposal is an outgrowth of a previous NSF grant and a smaller trial project, and seeks to extend them. Some of the groups co-sponsoring this proposal are an outgrowth of the previous grant, as are the co- directors. This project is appropriate for the Teacher Enhancement Program because of its plan to enhance the science teaching of a large number of upper elementary and middle school teachers Non-NSF cost-sharing is approximately 38% of the amount requested from NSF.