After naps we did another activity because I really wanted to try it! This activity was fun to watch but lasted no time at all! I found this activity at Growing a Jeweled Rose. She said after the bags exploded her kids played with the "chalk" that remained. My driveway slants too much so all the liquid just ran down to the street. I also didn't have a lot of corn starch left so maybe it wasn't as thick as hers? Here's how you make the exploding paint bags.
In a zip lock sandwich bag mix vinegar, warm water and cornstarch to fill up about a 1/3 of the bag. You want more vinegar than other ingredients. Add food coloring. Cut a paper towel in fourths. Put a tablespoon or two on the paper towel and found in the sides to make a packet.
Outside open up the sandwich bag (just at the corner), drop in the packet of baking soda and close the zip lock. Put the bag down and watch what happens. It really is fun to watch!