Alka-Seltzer Rockets

What you need:

• Film canister

• Water

• Alka-Seltzer

• Paper towels

What you do:

1. Fill the film canister with 1/3 of water.

2. Now, it's time to work quickly! Drop in half a tablet of Alka-Seltzer and snap the lid on to the film canister.

3. Flip the canister over so that the lid is on the bottom and set it down.

4. Step back and watch what happens!

Questions to ask:

1. What do you think would happen if you use more or less water?

2. What would happen if you used more or less of the Alka-Seltzer tablet

3. Do you think there would be a difference between using hot or cold water?

What's the science:

As the Alka-Seltzer tablet fizzes in the film canister, carbon dioxide is released. Pressure from the gas builds and builds, eventually popping the lid off. The thrust—or push—of your rocket is related to how much pressure builds up inside the canister before the top pops off.