The premise of a scavenger hunt: Start at any lettered question that's taped around the classroom and write the letter down on paper or a whiteboard. Solve the question and the correct answer choice will lead you to the next question to find. Continue until you've answered all questions. If done correctly, the last question's answer will bring you back to the letter you began with. Most students won't begin with the first letter, but can figure out the secret word that the letters spell by the end. The word also makes it easy for me to check their answers no matter what letters they've been to because I know what order the letters should be in.
Here's my Geometry Right Triangle Trig Scavenger Hunt.