Have you tried partner painting or friendship painting yet? It is a great way for children to learn about cooperation and team work. I like to introduce it at the beginning of the year to help the children build connections with each other. All you need is a couple kiddos, a large sheet of paper and some paint. You can even join in the fun!
Painting with their feet is a fun partner activity too. I would suggest making sure the kids have something to hold on to though. The paint can get slippery.