[Kyle]

Going along with the car, and fan idea, you can make "land boats", have the kids make a car, or use a dollar store car and they can make and design sails for them. to add a little fun have the boats drive up an incline rather then a straight lane.

Also one of my favorite things I remember doing was a parashoot drop. have the teams make a design for parashoots that hold something, action figure, egg or what ever and see who can make the one that drops the slowest, safest, most complex design etc. all you need is a ladder , or stair tower and an adult who isn't afraid of heights.