The purpose of this project is to design and evaluate a cost-effective model program for improving science instruction in all 125 elementary classrooms of the Cotati-Rohnert Park Unified School District. Project MAST will adapt existing effective elementary teaching materials and methods to meet the curricular objectives established by the school district in its program to implement a comprehensive and articulated elementary science program. This two-year project will devote its first year training teachers to adapt effective teaching techniques and materials to the specific objectives identified by the school district and to produce instructional kits, which will include both physical teaching materials and teacher instruction and background information. This design and production effort will be carried out by a team of school district teachers and university specialists in elementary science education. Special emphasis will be placed on including many district teachers in field trials and evaluation of teaching materials in order to encourage teachers to commit to the project. The second year of Project MAST will be devoted to inservice training of all 125 district elementary teachers. District science mentor teachers will be responsible for providing four days of training for each teacher in the use of the instructional kits and for providing support as required. The evaluation of the project will include a longitudinal analysis of the actual classroom use of the instructional units and analysis of anecdotal evidence concerning the reactions of teachers to the project.