Spirolaterals

Spirolaterals are a great example of geometric art arising from the iteration of a procedure. They’re simple to explain, take concentration to execute, and give rise to interesting math questions.

In a nutshell:

1. Take a small set of counting numbers, perhaps {1, 3, 2}.
2. On graph paper, draw a line one unit long.
3. Turn counter-clockwise and make the next line three units long. Turn counter-clockwise again and make the next line two units long.

This set of numbers {1, 3, 2} is closed. Additional iterations simply overwrite the existing lines.