The slime will start out as a highly flexible polymer. You can stretch it and watch it flow. As you work it more, the slime will become stiffer and more like putty. Then you can shape it and mold it, though it will lose its shape over time. Don’t eat your slime and don’t leave it on surfaces that could be stained by the food coloring.
Store your slime in a sealed ziplock bag, preferably in the refrigerator. Insect pests will leave slime alone because borax is a natural pesticide, but you’ll want to chill the slime to prevent mold growth if you live in an area with high mold count. The main danger to your slime is evaporation, so keep it sealed when you’re not using it.
Foam is awesome! The foam you made is special because each tiny foam bubble is filled with oxygen. The yeast acted as a catalyst (a helper) to remove the oxygen from the hydrogen peroxide. Since it did this very fast, it created lots and lots of bubbles. Did you notice the bottle got warm. Your experiment created a reaction called an Exothermic Reaction – that means it not only created foam, it created heat! The foam produced is just water, soap, and oxygen so you can clean it up with a sponge and pour any extra liquid left in the bottle down the drain.
This experiment is sometimes called “Elephant’s Toothpaste” because it looks like toothpaste coming out of a tube, but don’t get the foam in your mouth!