Ever wondered how to make elephant’s toothpaste? (Ok, it’s not scientifically what elephants use to clean their teeth but the effect looks like what might happen if elephants did use toothpaste). In fact, this experiment is a chemical reaction which causes a rapid expansion of foam – enough for an elephant! Warning! Hydrogen peroxide can be dangerous if swallowed/can irritate skin and adult supervision is required throughout the experiment. Gloves should be worn.

You will need:

  • bottle of 6% or 9% hydrogen peroxide liquid (sold in chemists),
  • 1 TBS of fast acting dry yeast
  • 3 TBS warm water
  • 1 TSP washing up liquid
  • Food colouring or paint
  • Empty plastic bottle
  • Gloves


  • Put your rubber gloves on!
  • Pour 200ml (probably the whole bottle) hydrogen peroxide into the empty bottle (you might need a funnel here).
  • Dribble food colouring or paint down the side of the bottle
  • Add washing up liquid and swirl
  • In a separate cup or bowl, mix the yeast and warm water and stir
  • With the bottle on a safe, hard surface (preferably outside or in a tray) pour the warm yeast mixture in to the bottle and stand well back!
Have fun with this easy experiment which shows the reaction that occurs when hydrogen peroxide is  mixed with washing up liquid. A catalyst, in this case yeast, is added to make the hydrogen peroxide decompose very quickly. Hydrogen peroxide breaks down into oxygen and water. As a small amount of hydrogen peroxide generates a large volume of oxygen, the oxygen quickly pushes out of the container. The soapy water traps the oxygen, creating bubbles, and turns into foam.

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