George Hart

These three beautiful constructions are challenging assembly puzzles. Their apparent simplicity is deceiving, so building them will stretch your visualization and problem-solving skills. Each derives from a familiar regular polyhedron---the tetrahedron, cube, and dodecahedron, respectively---yet the faces join together in a surprising way. Instead of connecting edge-to-edge as polyhedral faces do, these polygons lock together by "linking elbows" in a symmetric entanglement. Once they are built and handled for a while, their internal logic becomes clearer and they serve to illustrate the richness of the structures to be found in the mathematical world. For detailed instructions, see http://MakingMathVisible.com