Laser Beam Challenge - Set up a laser obstacle course in a hallway with crepe paper. The crepe paper will tear if the kids bump into it, letting them know they weren't able to get through the course. For added fun, do this in the dark with glow sticks!
Masses of ways to repurpose light bulbs! In an earlier pin I found how she is getting the bottom out of the light bulb and labeled it such so you can look in the board here for it. No waste of old light bulbs.