I frequently include the following in my first homework assignment:
Build some interesting pictures in DrRacket, using the material of chapters 1-3. Turn them in, along with the Racket expressions you used to build them, by e-mail. If you use copied images (e.g. clip-art or photos), tell me where you got them.The following are some of the pictures produced by students in the first few weeks of their first programming class. By permission.
(Actually, this one is by a high school student, a few weeks into his first programming course, using Picturing Programs.)