Science Buddies: "Ask an Expert"

Hello, a friend and me are doing a experiment with second graders and we would like to do elephant's toothpaste. We have all the materials and the procdure, but we have no idea how to explain it to second graders. Here are some questions we have:
How do you make it shoot up?
How do you make it fun for little kids?
Does it matter what kind of yeast we use?
How do we convince the second graders's treacher?

Hi,

Sounds like a fun project! The reason elephant's toothpaste bubbles up is because hydrogen peroxide, which splits into water and oxygen, performs this reaction (i.e. splits into water and oxygen) faster when you add yeast. Yeast is called a "catalyst" because it speeds up the reaction/splitting up of water and oxygen. That's why the foam rises up: all the oxygen bubbles generated are causing it to bubble out of the container. You could also tell them that oxygen is in the air we breathe and is the main gas that helps keep us alive. As for your second question, I think the project will be perfectly fun as it is, but you can let the second graders pour the yeast and water into the bottle themselves and watch the reaction occur. If possible, you could also acquire lab goggles for all the kids (maybe borrow them from a high school?) so that they can get into the scientific spirit. Also, it doesn't matter what yeast you use. As for the teacher, if you explain the project to her and its scientific benefit, I think he/she would probably be willing. However, I can't speak for the teacher. Good luck!

Sincerely,
Elena