Project LEARN will open a working national laboratory to 40 middle/junior-high school teachers, giving them first-hand experience in what it is like to do science. It will invite five-member teacher teams from eight varied urban and rural districts in California, Colorado, North Carolina, and Texas. One team member will be a master teacher, and the others will be promising but less experienced; the project especially targets population groups underrepresented in scientific professions. The teachers will attend three consecutive summer workshops at the National Center for Atmosphere Research (NCAR), where they will do experiments, bolster their understanding of background scientific concepts, and learn effective hands-on methodologies. With guidance from the principal investigators, from master teachers, and from NCAR scientists, they will translate what they learn into classroom activities for their own districts, with their different curricula and different student populations. Project LEARN will also provide leadership training, so as to prepare teachers to lead inservices in their home districts and to catalyze change in district-wide teaching strategies. As each participant excites colleagues who attend district inservices and they all change the way they teach, the benefits of Project LEARN will be greatly multiplied. In the fourth and final year of the project a one-week workshop will focus on intensive leadership training for giving peer-led workshops. It will synthesize experiences gained by teachers in the two previous years as they led such workshops and plan a third inservice for their local district. The intent is that such inservices can become a regular part of the districts professional development program. Cost sharing equals 47% of the NSF award.