Alka-Seltzer Rockets

This morning Yr.6 caused a chemical reaction by mixing Alka-Seltzer tablets and water, this reaction creates carbon dioxide.  They put the tablets into a sealed film canister and found that the pressure build up caused the canisters to fire up into the air like a rocket.  The children worked in pairs to create the right conditions for their rocket to fire between thirty and forty seconds after creation.  They considered why experiments needed to be repeatable if they were to prove scientific principles.