This is an incredibly simple project, but really fascinating and fun to do. Here’s what you need:
- Vegetable oil
- Food coloring (we tried liquid watercolor and it didn’t really work that well)
- An empty water or soda bottle (16 or 20oz)
- Alka Seltzer tablets
Simply fill your bottle about 3/4 full of oil. Mix water and food coloring together, then add this mixture to the oil in the bottle until it’s almost full — leave about an inch at the top. Watch the colored water make its way to the bottom. Then, break up a tablet of Alka Seltzer and drop it bit by bit into the bottle. Magic! We experimented with breaking the tablets into bitty little pieces and into bigger pieces to see which would make more bubbles.
We had about 20 children do the project over the course of 90 minutes. The youngest was about three, the oldest about 12, and they all really loved it. Since we were here in the store, I lined our table with paper towels and had the children work in aluminum roasting pans — just in case of a spill.