This paper describes the genesis and purpose of our geometry methods course, focusing on a geometry-teaching technology we created using NVIDIA[R] Chameleon demonstration. This article presents examples from a sequence of lessons centered about a 3D computer graphics demonstration of the chameleon and its geometry. In addition, we present data addressing the tools' effectiveness at helping preservice teachers learning geometric concepts, as well as changing preservice teachers' perceptions and attitudes about geometry. (Contains 2 tables and 4 figures.)