Simple Programs in Turtle Geometry
This Demonstration explores simple programs in turtle geometry, where an unseen turtle moves and traces a path according to provided instructions. If only one move-turn pair is used, the size of the forward step will have no affect on the image.[more]
As an example, to draw a pentagon of side length 10, use one move-turn pair with 5 repetitions and set "turn 1" to right 72. As your instructions become more complicated, the turtle's paths will become more intricate.[less]
 H. Abelson and A. diSessa, Turtle Geometry: The Computer as a Medium for Exploring Mathematics, Cambridge, MA: MIT Press, 1980.