Platonic Solids Icosohedron TetrahedronCubeOctahedron Dodecahedron

If you have not completed the pre- test, please do so before continuing.

You boil it in sawdust: You salt it in glue: You condense it with locusts and tape: Still keeping one principal object in view- To preserve its symmetrical shape. From Lewis Carroll The Hunting of the Shark

Definitions A regular polygon has all sides equal and all angles equal. Regular polyhedron have all faces that are regular polygons and the same number of edges meet at each vertex.

Background Information Greek philosopher Plato seems to have been the first to discover that there are only 5 regular polyhedra, and to this discovery he attached cosmic significance. As with most Greeks of his time, he believed that the universe was composed of 4 basic elements: Earth, air, fire and water. To Plato it was obvious that atoms of earth were tiny, invisible cubes; fire were tiny tetrahedrons; air were octahedrons; water were icosahedrons; and the universe was a decahedron.

The Platonic Solids Earth/ Cube Tetrhedron/Fire Octahedron/Air Icosahedron /Water Dodecahedron/ Universe

Then and Now The universe represented to Plato a cosmos, with a pattern of animal figures. Scholars have speculated that this refers to the twelve signs of the zodiac. Others point out that each of the twelve faces of the dodecahedron is a regular pentagon, embodying the divine golden proportion. Whatever the truth it probably held more significance during Plato’s time than it does today.

Project This activity will present the geometric standards within the group project. Be sure to read through all the information in the group project handout before you begin. Discuss each numbered item before you go on to the next number. You MUST fill in the job description information before you pick up your Platonic Solids instructions handout. Your groups have been chosen for you. Do not leave your group. Be sure to visit the internet sites provided at the end of your group project handout.

Building an Equilateral Triangle Remove three straws from your box of straws. Pick up one straw with your left hand being sure that the end closest to the bend points up. Be sure to grasp the straw so that you are protecting the hinge. Fold the short end into a “v” shape. Be sure to crease the fold several times. Follow the same process with all three straws. Insert the short end of each straw into the long end of one of the other three straws. You have constructed an equilateral triangle.

Time to Work Pick up your packets and report to your group area. Organize quickly and begin to build your models. You will have one and one-half class periods to complete the building of the models. Be sure to read everything in your student packet carefully.