I saw the idea on Pinterest to have the kids use eye droppers to drop colored vinegar onto a solid sheet of baking soda and knew my kids would love it. It was so much fun! The pin claimed that it provided 2 hours of fun for a 2-year-old. I just can't even imagine that unless you have an incredibly neat and meticulous 2-year-old. But we got a good 45 minutes, and that is unheard of around here!
I have a handful of Dollar Tree cookie sheets, and I used those for this project. I sprinkled a 1/4" thick sheet of baking soda to cover each cookie sheet. Then I filled ice cube trays with vinegar and colored a handful of them with food coloring. Each kid got an eyedropper and went to town. They both loved the fizz as the vinegar hit the baking soda. My 27-month-old boy got a little baking soda on the end of his dropper and soon learned that it made the vinegar fizz when he dipped it back in for more. He soon flip-flopped the activity and scooped baking soda into each ice cube compartment to create mini volcanoes. He was thrilled! We just stuck his ice cube tray in the middle of his cookie sheet, and he had the freedom to go to town.