This isn’t really a project per se, but more of a technique that Beckett really enjoyed, and I like to think he absorbed all sorts of geometry theory while participating.
I happened to find a stencil full of circles and pulled it out one hot day while we were outside. I grabbed a big piece of white poster board, and some watercolor and finger paints. We started off with the circles and watercolors. He was very focused on trying to paint inside the circles.
When attention spans started to wane, we broke out the finger paints and got all loose and expressionistic. It was sort of a 2 for one project.
I think he was pretty careful with the finger paints based on trying to mimic the circles he was painting with the watercolors. I like this idea of using two different but similar materials to make the same shapes. It will give kids a feel for how different types of paint feel and act differently.
With a slightly older child, you could probably add on painting around cans to get a circle another way, and then ink up the bottoms of the cans to make circle prints. You’d be rewarded with a nice big painting of circles to display proudly in your home.