Preschool Powol Packets: Science Experiment: Elephant Toothpaste. In bowl mix 2 Tbsp warm H2O w/ 1 tsp yeast. In empty soda bottle mix 1/2 c at least 6% hydrogen peroxide (20 volume cream developer from sally' or 8% at Amazon) with a squirt of dish sop & 4 -5 drops food coloring. Pour yeast into bottle & watch the reaction. The soap catches the oxygen release & causes the bubbles & foam.