If your class or program has anything to do with the Internet, consider building a fully viable website from code. Beginners and those in classes with a low course code can work only with HTML. More advanced students should attempt more complex sites, employing cascading style sheets (CSS), Javascript and other more complicated coding.
Games are versatile computer sciences projects, as the games can be as simple or as complicated as you need them to be based on the level of class that you are in and your own experience in game programming and design. It can be particularly gratifying, too, because when you are done you can enjoy your own creation, and can put it on the Internet for other to enjoy. Games suitable for beginning students include tic-tac-toe or a simple virtual tennis game. Intermediate students can try an arcade game clone or a puzzle game. More advanced students can try their hands at a role playing game or a basic platformer.
Build a computer from scratch parts. If you are a younger student, get a kit that tells you how to put the computer together step by step. If you are more advanced and the project rules allow it, build your computer from components instead of a kit, and make deviations from a standard computer, reconfiguring things to work in different, interesting ways.