A lightbulb went off in my head, though, when I realized we could try them in our sketchbooks. We have "free draw" at last twice a week, and on those days, the children can finish work they've done before or start something new. I've realized that if I am trying to give a specific prompt, I need to have the children find a specific page in their books using a visual cue (like the circles last year). So, to go along with the verbal prompt of "draw a picture of you", I had drawn a large black rectangle on a page in each child's book. And everyone did draw a picture of themselves. I suppose I had envisioned the rectangle acting as a frame, but (as always) the children put their own spin on it.
I could not stop smiling when I saw the ones that used the rectangle as the body.
I think that when I present the prompt of making a self portrait again, we will be able to use a separate piece of paper, but maybe we won't bother. The sketchbooks are a way to see the progression of children's work; and it is their own creative space. Perhaps we need larger sketchbooks - I have always made them this size, and I'm not sure why!
Regardless of where we make them, I see the value in this work year after year.