Do you see your shadow?

When I picked Griffin up from school yesterday he told me they were reading a book about the bear seeing his shadow (don't know the actual name of the book). Griffin mentioned the book several times so apparently he liked it. His teacher told me he had it all figured out. They talked about shadows in the morning and in the afternoon when they were outside, she asked if they could see their shadows. She said Griffin promptly responded "no" and when she asked why. He said it was because of the clouds. She said he figured it out before they even talked about it (they had talked about needing the sun for shadows, but they were going to talk about what happens with clouds today).

I have no clue how he figured that out. Their little brains certainly soak up a lot of information--and it makes you doubly aware of what you are exposing them to!