When my daughter was fifteen months, I accidently discovered a great art activity. I had put her in her highchair to color with some crayons. When I went to tape down the construction paper, her high chair tray was still a bit wet and the paper changed colors where the water touched the paper. She was fascinated by this and kept yelling “That, That” (her all purpose word). I then dried off the table and taped down a fresh piece of construction paper. I then got her a paint brush and put some water in a no spill container. Note: These are must have for any painting project with kids and I highly recommend them. I then showed her how to tip the paint brush into the water and paint on the construction paper with the water. She was fascinated by this and we spent hours over the next few weeks painting with water.
Once she got the hang of it, we graduated to water colors. I would put water in all of the colors of paint for her before we got started to make it easier. To keep the mess to a minimum I would tape down the paper and we would always do this project in the high chair. I was surprised how she was able to paint with water colors at such a young age and how relatively mess free it was. She was much more engrossed in this than finger painting, which seemed to take an hour of clean up for 5 minutes of art.