I gave Maia and her friends some sharpies the other day and let them draw on our canvas patio "walls". I said they could draw as big or as small as they wanted. They mostly drew big.
They made a lot of spirals, as on this artwork, as well as some stick figures.
While I liked the idea of having the canvases blank (or washable) so they can be reused over and over again, I also liked the idea of adding permanent line drawings over the course of the summer. I'm sure we'll be doing lots of more ephemeral art over the line drawings, including some more spray painting.