Fun science with quick acting yeast

How does yeast work? This is a fun was to entertain the kids and it is educational! Science is all around us including the science of cooking and baking. Yeast is a little single cellular organism that we use to bake with. In this experiment, we look at how we can wake up the little organisms!

You will need

  1. 2 plastic bottles
  2. 2 balloons
  3. warm water
  4. dried yeast (fast action)
  5. sugar


  1. add the same amount of warm water to both bottles
  2. add the same amount (1 teaspoon) of dried yeast to both bottles
  3. to one bottle add 2 teaspoons of sugar
  4. mix both bottles and then place a deflated balloon over each bottleneck
  5. leave for 60 minutes, checking on it every 10 minutes to see how it is getting on

Check out our YouTube video on the experiment here:

How does yeast work: Results

In the bottle with the yeast and warm water nothing happens. But in the bottle with yeast, warm water and sugar the balloon inflates over time!

Yeast is activated or woken up by warm water and then the sugar acts as its food. The yeast and sugar produce a gas (carbon dioxide). It is the carbon dioxide that gets trapped in the balloon blowing it up. This is similar to when the gas gets caught in the bread dough when it is proving. The air pockets get caught in the dough and cause the bread to rise and be light.

This experiment helps explain why bread needs yeast and sugar to rise.

Dietitian's Life EnjoyIf you have a go yourself, let us know how you got on in the comments below or post us a photo on social media! I hope your kids can tell you how yeast works now!

Looking for more fun? Check out our kid friendly banana and raspberry muffin recipe.

Have fun!