I'm sharing the book "Knuffle Bunny Too" by Mo Willems with them as an introduction to line and shape. The main characters, Trixie and Sonja, are in TK, so it's a perfect fit:) After reading the story to them, I ask them if they have a toy that they love like the main characters of the book do. I encourage them to picture it their head.
My little artists then look at their practice drawing and refine it on a larger sheet of drawing paper. I tell them that it's okay if the drawing looks a bit different than the first one and I talk about adding more details to their drawings because their paper is bigger.
This has been a great opening activity- it allows them to share something personal and it gives me an idea where students are coming in at in terms of fine motor control. It's also a nice intro to the planning stage in art.