Shadow
When I was a child, I played with mirrors, shadows and light. I would go to bed with a mirror and felt pens draw on it and see what kind of images I would create on my walls or ceiling with the reflections. I think shadows are equally interesting. They always give you something interesting to learn from. That is why my little shadow here is playing with my robot. If only my shadows played with me like that...... oh wait..... they did.