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!
Diy Cardboard Slide ~When I was a kid, we did this! ***One improvement: make the cardboard about a foot narrower than the stair width, so that there is space for the kids to climb up on the stairs rather than the cardboard slide.