It will keep your kids busy for at least 20-30 minutes if you use a spray bottle or pipette to make a bubbling or fizzing rainbow. This is a great fine motor skill as well as science fun.
Jake and Cate had so much fun doing the Shamrock science I set up another fun science twist with colors. The key is to set it up and add a little twist each time to keep the kids interested in it.
If your kids love science and experimenting be sure to check out all the fun you can have with science and kool-aid