This one was great because it's a little art, a little science, and only required items I already had on hand. I first learned of this clever trick here. Of course, we already knew about the splendid things that can happen with baking soda and vinegar, but it never would have occurred to me to add a little food coloring. That's all this is--a pan of baking soda, vinegar with food coloring, and a few eye droppers (in our case, leftover pediatric medicine dispensers).
Two planned home activities before noon on a Monday. Not bad for Day One of Camp Mommy.