I've been reaching back to my own childhood a lot lately to come up with fun yet simple activities to share with the kids. I remembered playing with a homemade paint bag at a friend's house as a child. Thinking back, my friend's mom probably didn't trust us with paints so she poured some into a plastic bag and taped the top shut.
You can create the same thing using a gallon-sized freezer bag and some tempera paint. Make sure the paint you use is not too runny. Spread the paint around evenly in the bag and let your child draw with his finger. You can let your child practice drawing shapes, numbers and letters over and over. And as long as the bag stays closed (tape it shut if you want) you can avoid a mess.
Image: Lets Explore