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.
hot_air_ballon_ October, the skies are filled with 750 hot air balloons for Albuquerque’s International Hot Air Ballon Fiesta. The 9 day event is the largest ballon festival in the world. Just before sunrise, 750 balloons take flight in only two hours.