Project SITE (Successful Inservice through Turnkey Education) is an exemplary staff development program which provides training in mathematics content and appropriate methodology to elementary school teachers (grades 2-6). Participants interact with manipulative materials, taking an active role in their own concept development and learning of mathematical skills. Effective instruction in metric measurement must incorporate a number of mathematics concepts and skills, such as estimation, place value, decimals, area, perimeter, and volume, and Project SITE curricula includes these as well as several other topics. Participants receive 4 days of mathematics instruction, spaced over a period of time, to allow for classroom tryouts of activities and materials. Upon completion of the training sessions, the second phase of the inservice program begins. This phase involves the training of other teachers in each participating school building or district via the multiplier approach. The original participants, or turnkey teachers, conduct inservice programs for their colleagues. The turnkey workshops are conducted during various time periods, and the presence of the turnkey trainers in each participating building permits the program to respond to individual school needs. The Project SITE staff development program has proven to be an efficient means of providing mathematics instruction to elementary school teachers. (JMK)