My painting class thought I had lost my mind when I told them to paint an entire picture with only a palette knife. And then they really moaned and groaned when I handed them 18x24 paper.
A few years ago I bought several of those plastic knife palette knife kits (I don't remember my original plan) but I thought we should open them up and use them. And what better way to challenge my students than ask them to paint a picture with just the knives.
At first they complained, but once they figured out a technique they started to get into the picture. Not all of them are done yet, but I wanted to show off some of them. I also took some pictures of the kids working. I need to do more of that.