This three-year project develops 40 5th and 6th grade mentor teachers and 480 partner teachers from grades K-6 in prealgebra, geometry, and data analysis content with inquiry-based methodology and alternative assessments throughout. In this California State University- Northridge/Los Angeles Unified School District partnership, special attention is given to skills in teaching minority and limited-English students who comprise the majority of the local population. Participants experience residential institutes, workshops, midweek seminars, and teacher-leader inservice opportunities, using the "sandwich" model (NCTM, 1990 Yearbook) of classroom trials between the workshops and followup sessions.