Combining coursework with an apprenticeship program, this 2.5-year project will prepare "crossover" teachers from other disciplines to teach middle school mathematics and science. Each summer, the 56 participants will attend a three-week summer workshop at which they will study appropriate mathematics and science content and related teaching strategies. The 28 science teachers will focus on chemistry and physics, while the 28 mathematics teachers will study problem-solving, probability and statistics, and other topics in middle school curriculum. Teams of four teachers from the same district will be led by a master teacher who will provide guidance and support during the academic year. Academic-year activities will also include eight meetings of participants with the project staff. The evaluation will identify those characteristics that promote the success of "crossover" teachers in their new role. The university and the school districts are contributing in cost- sharing an amount equal to 32% of the NSF award.