Yeast Balloons

Using yeast, sugar and water, you can blow up balloons. (It might take a little longer than the usual methods!)



  • A packet of yeast
  • A small, clean, clear, plastic pop bottle (16 oz. or smaller)
  • 1 teaspoon of sugar
  • Some warm water
  • A small balloon



  1. Fill the bottle up with about one inch of warm water.
  2. Add all of the yeast packet and gently swirl the bottle a few seconds.
  3. Add the sugar and swirl it around some more.
  4. Blow up the balloon a few times to stretch it out then place the neck of the balloon over the neck of the bottle.
  5. Let the bottle sit in a warm place for about 20 minutes


The science

As yeast is a living organism and given the right conditions, it respires. As the yeast eats the sugar, it releases a gas called carbon dioxide. The gas fills the bottle and then fills the balloon as more gas is created.