with vinegar and baking soda.
Random Guys experiment and SensiGirls formulations ended up getting put together and this is what we got.
SensiGirl stuck with this project for an hour, which for her is quite the accomplishment. We were able to keep most of the mess in the baking pans. I found they are better for containing messes than the trays that the used in preschool and ECFE.