It's a bird, it's a Plane!

One of things that Tammy came up with when she was about 5 or so. We were outside and all of a sudden, she came running to me saying, "look, mommy, look, hurry", I asked her what I was supposed to be looking at (she was pointing to the sky). She said, "look, see that? A plane bumped into the sky and scratched it"! She saw one of the big white "marks" that the airplanes make across the sky while flying and thought the plane had already bumped into the sky.