This project is a five year program that will provide in- service education for high school and middle school biology teachers. Project goals are to update teachers' content knowledge in the biological sciences, increase their research experience, and increase their experience developing and using hands-on student activities. Innovative courses for a new master's degree in biology teaching will be tested. In addition, the project will promote continuing collaboration between precollege and university science faculty of the University of Arizona. Activities for participating teachers to be offered at the University of Arizona include the study of exemplary curricula,the study and modification of the Introductory Biology laboratories, and research opportunities in biology and education. Interactive courses on pedagogy in biology, developing hands-on lessons and, special topics in biology will also be offered. All activities are designed to maximize interaction between precollege science teachers and university faculty in the biological sciences and education. Stipends will be provided for participants and graduate credit will be given for all activities. Approximately 150 teachers in Tucson and surrounding communities will participate in project activities. A network of Master Teachers will be established from program participants. Master Teachers will conduct one-week workshops at the University of Arizona and at Northern Arizona University for other teachers in the state which will be cost-shared by local school districts. These workshops will serve approximately 270 additional teachers in Arizona. Cost sharing equals 98.4 % of the NSF award.