Now, make a rocket with a film canister! Kids end up with a stellar toy that they can reuse!
Science: "When you add the water it starts to dissolve the alka-seltzer tablet. This creates a gas call carbon dioxide. As the carbon dioxide is being released, it creates pressure inside the film canister. The more gas that is made, the more pressure builds up until the cap it blasted down and the rocket is blasted up." - Science Bob (click here for instructions)