Assignments for Introductory Level Processing
I did a 4 half day "camp" for two high school girls a couple summers ago. We spent the first two days doing Processing programs. Etch-A-Sketch and Tron are a couple good assignments for beginners. The Etch-A-Sketch simulation leads nicely into making a game based on the light cycle scene in the movie Tron. 

Here is some information about what we did in the camp