Geospatial and Robotics Technologies for the 21st Century (GEAR-Tech-21), teaches science, technology, engineering and mathematics (STEM) through robotics, global positioning systems (GPS), and geographic information systems (GIS) activities for youth in grades 5-8. Participants use a robotics kit, handheld GPS devices, and GIS technology to explore STEM related careers. It has been used by classrooms, afterschool and community-based clubs, competitive robotics teams, residential and day camps. The hybrid learning experience that GEAR-Tech-21 has created brings together an on-line curriculum, digital manipulatives and real-world experiences--which have resulted in new roles for learners and instructors. The instructor's role has shifted from instructing and leading to guiding and supporting learners. This paper explores how GEAR-Tech-21 is developing new strategies in professional development to support our volunteers in this new role. (Contains 3 figures and 2 tables.) [For the complete proceedings, "EdMedia 2012: World Conference on Educational Multimedia, Hypermedia and Telecommunications. Proceedings (Denver, Colorado, June 26-29, 2012)," see ED539862.]