Paint in a Bag is activity I remember doing in preschool as a little kid. We practiced writing letters with paint mess free! I was reminded of this great project from Let's Explore Here.
We started with each primary color in a baggie taped to our table. As we added colors and learned about mixing colors to make new ones they are sometimes hard to see as the color as mixing. So grand idea..... Tape them to the deck door (or window) the way the light shine through as you are mixing is beautiful.
Monkey 1 was very proud of her color mixing creations!! Monkey 2 mostly enjoyed the fact that she could actually touch a plastic baggie (very closely supervised). She eventually realized she could move the colors around, but I would recommend double bagging these for the little ones... You don't realize how strong their little fingers are until they break open a bag of paint, or pinch you with their painted fingers....! haha!