Riddle: You in the room to the left. There are three light switches in your room. You see a note that says "To escape this place, you must tell me which switch goes to which of the three lights in the room across the hall. But, once you get halfway through the hallway, a wall will block your path back to the room." You need to figure out how it'll work.
Answer: The answer is Science! I was shown this by a third grade substitute teacher awhile back and have hardly found anyone who can figure it out. And you'll need to discuss it on the forums, because the answer is not in easy reach.