I love employing hands-on activities for my students.  The subject of Geometry lends itself perfectly well to this teaching technique.  When a student applies new knowledge through drawing, or creating 2-d and 3-d objects, retention and understanding are increased and reinforced.  It is also more fun for the students.  Rather than memorizing mathematical vocabulary by rote, students use the new words during the course of their geometric constructions and 3-d visualizations. This makes the learning of new words feel more natural, and thus more likely to become a part of their regular vocabulary.