Materials:

• Coke bottle
• Water
• Baking soda
• Teaspoon
• Straw
• Lemon
• Balloon

Instructions:

• Show the children how a balloon grows with gas
• Take a coke bottle
• Fill the bottle up with 40ml water and 1 teaspoon of baking soda
• Mix together with a straw
• Add lemon juice.
• Loosen a balloon and place on bottle.
• Watch the balloon grow