Film canister rockets are always pretty amazing considering all that powers them is a little bit of Alka-seltzer and water. The launching time is always a bit unpredictable and that just adds to the fun.

What you need:

• Paper, Index cards or cardstock,
• Translucent film canister, Tape,
• Scissors, Effervescing antacid tablet,
• Water and Paper towels

What to do:

1. Wrap and tape a tube of paper around the film canister. The lid of the canister goes down.
2. Cut fins from the index cards and tape to the rocket.
3. Make a nose cone by cutting a circle out of paper. Cut out a pie shape from the circle and twist the paper into a cone. Tape the cone together. Then tape it on the open end of the paper tube.
4. Turn the rocket upside down and fill the canister 1/3 full with water.
5. Work quickly! Drop in a 1/2 tablet and snap the lid on tight.
6. Stand the rocket upright and stand back!

CAUTION: Be careful when launching your rocket. Stand back and don’t point it at anyone.

What’s the science?
As the antacid tablet “fizzes” carbon dioxide inside the canister, pressure from the gas builds and eventually pops the lid off. The amount of force, or push, created is related to the amount and speed of gas and water propelled from the canister.

What will happen if…

• you change the design of your rocket?
• you use more or less “fuel?”
• you use hot or cold water?

Choose one thing to change (that’s the variable), then predict what you think will  happen and test it.