We pulled out the old food coloring and water in an ice cube tray trick for a bit of painting fun. I explained to A at the beginning that he needed to rinse off the brush every time he dipped it into a new color otherwise it would spoil the colors. For the first five minutes I would say "Rinse!" each time his brush approached the paints. After that he was great at it...when he wanted to. Sometimes he would start at one end and dip his brush in every color just for fun. So the yellow was a bit green and the blue was turning purple. Oh well. He loved it.
At first I let him be creative and do what he wanted. After five pieces of paper I started drawing simple pictures for him to color in. He enjoyed both types of canvases. Several days later we did it again, but this time I made some 'educational' pictures to be colored: the number and letter we were studying for the week. It was an easy and fun activity for us both.