Art Sub Plans Elementary. All are designed for minimal impact on supplies. It requires no prep.
It requires no prep. And show the pictures. Students begin by sketching the outline of an object and then ruling blue horizontal lines across the piece of paper stopping at the edge of the object simulating the lines on a page.
There is also this resource by art sub lessons which has many pictures of real tree houses for inspiration.
It also gets them thinking about color choices. Nms painting restoration has contacted. From just a pencil to simple. Get your art sub plans organized so that any substitute teacher could walk in with little notice and teach a successful elementary art lesson.