Balloon Rockets - I've done this in several science camps I've conducted. Kids have fun with it. But, when the balloon deflates it may fall off the straw because it's surface area changes - another good thing to show and explain to kids.
This site has TONS of resources for structured play, beginning literacy activities, and hand-eye coordination broken down by age from birth and through school years. Stoplight Beanbag Toss - I Can Teach My Child! I own bean bags already!