1. Bottle of warm water (about 25 degrees celcius)
2. Packet of dried Yeast
3. 5 teaspoons of sugar
1. Put sugar into the warm water
2. Add Yeast
3. Strecth balloon over bottle.
What's going on:
When Yeast feeds on Glucose, it produces energy, carbon dioxide and a minute trace of alcohol. The carbon dioxide fills the balloon and eventually the balloon goes flying off.