A Teacher's Guide to Building the Icosahedron as a Class Project

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Next: Assembling the structure

## Coloring the faces

Once all twenty triangles are cut, label them according to the system 1N, 2N, 3N, 4N, 5N (the "North" pieces), 1S, 2S, 3S, 4S, 5S (the "South" pieces), 1E, 2E, 3E, 4E, 5E (the "East" pieces), and 1W, 2W, 3W, 4W, 5W (the "West" pieces). The sides that are labeled are the "back" sides of the triangles and will be inside the icosahedron. On the "front" side of the triangles, have your students create interesting mathematical patterns (e.g., spirals, fractals, symmetric structures) or draw something about their interests (sports, music, hobbies). If desired, the triangles can be colored according to the following scheme:

Color Triangles
Blue
Purple
Orange
Green
Red
1S, 2E, 4W, 5N
2S, 1E, 4E, 1N
3S, 3E, 1W, 2N
4S, 5E, 3W, 3N
5S, 2W, 5W, 4N

Table 1:   A coloration of the icosahedron.

See if your students can discover what makes this color scheme special? (Hint: Look closely at the colors around each vertex of the finished icosahedron.)