Pendulum Painting. This would be a great science based lesson for EOY. This was always one of my favorite projects in middle school and I still have all my "drawings" now. Great way to tie a lesson in with this and very inexpensive. - Heart-2-Home
Paint on foil. Be sure to add a small amount of dish washing liquid to your paint mix. Not only will that make cleaning up easier but it also helps the paint to stick to the foil better and not flake off when it dries.