This activity comes courtesy of Curt Prchal, a technology education instructor at Will James Middle School in Billings, Montana, and is sure to excite your kids' passion for learning. Children have always have liked making their own rockets, but the purpose of this activity is to get them to understand how they shoot up into the sky.

PROJECT:
To make and launch a homemade rocket

GOAL:
To understand the principles of rocket flight

AGES:
Four to 10

MATERIALS:
• Ball of string and scissors
• Large, cigar-shaped balloons
• Drinking straw
• Plastic mailing tape

STEP 1 Secure one end of the string loose end to the ceiling of a room with a bare floor. Unwind enough string to stretch to the floor plus an extra three or four inches and cut it. Thread the string through the drinking straw and tape the string securely to the floor.

STEP 2 Inflate a balloon and hold the end pinched shut. Tape it near the middle to the straw.

STEP 3 Give a dramatic countdown and, holding the balloon/straw assembly close to the floor, release! Watch how fast your balloon shoots to the ceiling and challenge your friends to rocket races.

Explain how the rocket is kept on its straight trajectory by the string and straw, and that the lifting thrust is produced by air escaping from the balloon in the opposite direction. This illustrates Newton's Third Law: for every action, there is an equal and opposite reaction.