Ms. Radle’s eighth graders investigate chemical and physical changes. Chemical changes change from one substance to another and are permanent. When we combined “high test” hydrogen peroxide with yeast, dish soap and food coloring, we permanently changed it into what we call elephant toothpaste! The yeast, hydrogen peroxide and dish soap combine to make an explosive foaming geyser unlike any of the separate ingredients. The food coloring makes only a physical change by affecting the color of the material. The students were actively involved and had fun!