How much math is in your computer science? I remember in my high school the assignments were mostly simple computational physics and math problems.
If you are interested in computational stuff, you might want to check out Project Euler. They have many, many problems, some of which are suited to a novice programmer (Problems like "How many numbers from 1 to 1000 are divisible by 3 or 5?"). They are all problems that can be solved in a multitude of different ways, and the first ones can be done with a few lines of efficient Perl.
Also, I don't know your students, but would it be fun to have a golf or speed competition? Let the kids see who can make the shortest or fastest solution, and then discuss it? Just tossing out ideas.
(I'll admit, I laughed at the anonymous monk's easy assignment)