My son loved doing this experiment and we had a great discussion around color mixing. We used all three primary colors and I let him pick which two secondary colors we should make. The tip about making the cups with color elevated is KEY! We didn’t do that to start and had to let them sit overnight. The next day they still were only halfway up the paper towel. Once I made the colored cups higher it went much faster but I think this is still a 2hr+ activity. Great visual and super easy at home activity!