"Look Mom!" I just love hearing that phrase. " I can see myself. Why?" He continued.
I think part of the intrigue was that this was a plastic lid, not a glass mirror. However, it works in just the same way. The light waves hit the smooth surface and then bounce back off. If you look very closely, a smooth surface is the same all over. Each individual ray of light bounces off at the same angle at which came to the object. The part of the lid that is not smooth, has little bumps on it. As the rays of light hit the little bumps in different places they bounce back in all different directions, and the picture is lost.