Yeast Balloon Science!

3.3 based on 720 ratings

What You Need:

  • Balloons
  • Narrow funnel
  • 1 tablespoon (15ml) active dry yeast
  • 1 teaspoon (5 ml) sugar
  • Measuring spoons
  • Measuring cup
  • Warm water
  • Ruler

What You Do:

  1. Place the bottom of a funnel into the opening of the balloon. You may need to stretch the opening of the balloon a little bit so that it fits.
  2. Have a parent (or a carefully supervised child), pour the yeast and the sugar into the balloon through the funnel. Then fill the measuring cup with warm water from the sink and carefully pour the water into the balloon.
  3. Remove the funnel from the opening of the balloon. Tie a knot in the balloon to keep the water-and-yeast mixture inside. Measure your balloon.
  4. Place the balloon in a warm place and wait. Measure your balloon again.

Now sit back and wait as the balloon gets bigger and bigger. Soon you'll have an awestruck child asking, “How did it do that?” Explain to your budding scientist that although it seems like magic, it's science. The yeast uses the sugar and warm water to grow, and as it grows it expands and gets bubbly. By being “bubbly” the yeast gives off carbon dioxide, the same gas that your body produces when you breathe, and the gas inflates the balloon.

You may not want to use this method to blow up a party's worth of balloons, but you'll certainly inflate your child's imagination and her love of science!

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