Planning a Halloween party this year and need some spooky activities to do? Or just looking for some light-hearted Halloween science experiments to do with the kids? I’ve got one to add to your list.

We call this witches’ brew at our house. You’ll create a sticky, brown, bubbly potion that will magically inflate a balloon. Draw a pumpkin or a bat on the balloon for added Halloween science fun!

Kick your Halloween science projects up a notch with this witches' brew experiment! Amaze the kids by magically inflating a balloon using common kitchen ingredients.

Witches’ Brew Science Experiment

*This post contains affiliate links. Please see our disclosure policy.

To make our witches’ brew we headed to the kitchen to gather the following ingredients:

  • 2 Tbsp dried yeast
  • 1 Tbsp sugar
  • 2 Tbsp lukewarm water
  • Glass bottle
  • Bowl half-full of lukewarm water
  • Party balloon

We mixed yeast, sugar, and water together in the bottle. To keep the mixture warm we set the bottle in the bowl of warm water.

We drew a small pumpkin on a balloon using a permanent marker and then stretched the balloon over the mouth of the bottle containing the yeast mixture. Then we placed it in the center of the table where it wouldn’t be disturbed and we could all see it.

I set a timer for every 10 minutes so we could check on its progress and watch the balloon get bigger and bigger!

Halloween Scie