The Physics Education Group at the University of Washington (UW) has been conducting special courses for K-12 teachers for more than 30 years. They have developed a sequence of academic-year courses for prospective elementary and middle school teachers and another sequence for prospective high school teachers. They also conduct an intensive NSF-funded six-week Summer Institute for Inservice Teachers that has similar goals. The materials used in both the preservice and inservice courses are drawn from Physics by Inquiry, a self-contained, laboratory-based curriculum that has been developed for use in university courses to prepare K-12 teachers to teach physics and physical science. The emphasis in this paper is on elementary and middle school. However, most of the discussion is applicable to the preparation of high school teachers.