You can find many designs for solar cookers online, but building one is not hard. So instead of giving step-by-step instructions, I boiled the project down to its basic components, and made figuring out the best way to create them part of the activity. Once you've got the hang of it, you might want to try to build a model big enough to make a meal. The directions on NASA's Climate Kids website are a good place to start.
Image: Kathy Ceceri