Shape 

Copyright David & Cynthia Thomas, 2009

Visualizing 3-Dimensional Objects--Directed Activity: Five Platonic Solids

Focus	Platonic Solids
Technologies	· The Platonic Solids model (See Figure 6.5) at the National Library of Virtual Manipulatives website
Background	A Platonic solid is a polyhedron all of whose faces are congruent regular polygons.  Furthermore, the same number of faces meet at every vertex.  The Platonic Solids are the tetrahedron, the cube, the octahedron, dodecahedron, and the icosahedron.    Figure 6.5: NLVM Platonic Solids Model
Tasks	The Greeks knew that there are only five platonic solids. Why is this so?  The answer is suggested by the following figures, each of which may be cut out and folded to produce a portion of a Platonic Solid.