Section 17.5 Teacher Note: Turtle Geometry
The turtle is actually useful for exploring a wide variety of ideas in geometry. The book Turtle Geometry 1 does a wonderful job of showing how turtles can be used to explore a wide variety of geometric, mathematical, and scientific ideas (e.g., using turtles to model insect behavior). The example pattern below is drawn from that book.
http://www.amazon.com/Turtle-Geometry-Mathematics-Artificial-Intelligence/dp/0262510375