Why, when I move this way while looking in my cereal bowl, do I see myself move the other way?
I'm paraphrasing (she's only 5.5 years old), and it took me a bit to understand what she was asking. She was eating cereal in a reflective, metal bowl and looking at her reflection on the inside (concave) part. When she moved left, her reflection moved right.
So she had observed this (kids seem infatuated with reflections), fine. But for her to ask this question, she had to know that in a flat mirror, the reflection follows you. I'm not sure how impressed to be, but I am pretty impressed.
I had a tough time explaining it without math, and I don't think she really understands the answer. I just hope she keeps asking questions.
Epilogue: I pulled out a flashlight to try and explain a bit...the kids love playing with it so it might make for a good gift.