• Protective eyewear is required for this project. DO NOT EAT any of the ingredients that are used or created. The product of the reaction may look like toothpaste but it is not safe to consume.

We made three – yes three! – awesome STEM-inspired Halloween decorations in this video! To make witch’s brew, also known as elephant toothpaste, view the video from 4:29-5:49.

A chemical reaction occurs when two different things are mixed together to make something completely new! In this project we are using hydrogen peroxide and active yeast to create elephant toothpaste with a witchy twist!

So how does it work? When hydrogen peroxide breaks down, it turns into oxygen (O2) and water (H2O). Normally this breakdown happens very slowly. But if you mix yeast with hydrogen peroxide, you create a chemical reaction where the hydrogen peroxide rapidly breaks down into water and oxygen gas. Adding dish soap to this chemical reaction makes it even more exciting. The bubbles formed by the oxygen gas, which would usually pop quickly, will get trapped and create lots of foam as the soap provides additional surface tension. This foam looks like a giant squeeze of toothpaste—almost big enough for an elephant(see Scientific American for more info)!

Ready to make this project at home or in your classroom? Watch the video for an overview, gather the materials listed at the right, and follow the instructions below!

Required Materials

  • protective eyewear
  • Warm water
  • 1 packet active yeast
  • 2 cups
  • cookie sheet or tray
  • 1/2 cup 3% hydrogen peroxide
  • 3-4 squirts dish soap
  • 2 drops food coloring

Step-By-Step Instructions

Step 1

Put on protective eyewear before starting this project.

Step 2

Use a cup to mix warm water with a packet of active yeast per the instructions on the packet. Set aside.

Step 3

Place a cup into the center of a cookie sheet or craft tray. Carefully add 1/2 cup of 3% hydrogen peroxide, three to four small squirts of dish soap; and two drops of food coloring to the cup.

Step 4

Pour the activated yeast into the hydrogen peroxide, soap, and food coloring mixture and watch your witch’s brew begin to bubble, bubble and bubble!