Homemade ice chalk is the perfect art, sensory, and science activity to keep the kids occupied on a hot summer day. Be prepared for the kids to get messy with this one. Their hands were turning colors even before they got the chalk out of the house. They had fun with it, but it didn't last long (even though the temp was in the low 70's that day). It was super easy to make, though, and the kids had fun mixing colors.