Interlocking geometric shapes (Geofix, Polydron, Polycontructo) help students to visualize and internalize key geometric concepts. Geometry and measurement become much more meaningful and exciting with these ready-to-use activities. Moving from 2D patterning to constructing complex 3D structures, each of the 15 activities features NCTM expectations, teaching instructions with extension activities, and reproducibles. Grades 3-6.