Learn how to make Elephant Toothpaste with Leo and Stella in this easy DIY Kids Science Experiment video. Here is step by step instructions on how to make elephant toothpaste: Carefully pour Hydrogen Peroxide 3% into the bottle. Add a big squirt of dish soap into the bottle, and swirl gently to mix. If you want to make your foam a single color, add a few drops of food colouring directly into the hydrogen peroxide, and swirl the bottle gently to mix. If you want to give your foam stripes like some toothpastes, put the drops along the inside rim of the bottle’s mouth. Let them drip down the inside of the bottle, but do not mix. mix together 2 tablespoons of yeast and 100g of warm water. Stir for about 30 seconds (it is better to do this step first so that the Yeast has time to activate). Pour the yeast mixture into the bottle then quickly step back, and watch your reaction go! What happens? You probably saw lots of bubbles and foam in this activity. When the hydrogen peroxide comes into contact with the yeast it starts breaking down into water and oxygen. Oxygen is a gas and therefore wants to escape the liquid. The dish soap that you added to your reaction, however, traps these gas bubbles, forming a foam. The reaction continues as long as there is some hydrogen peroxide and yeast left. Once one of them runs out it stops making new foam.