My boss used to host a science show on television, and I came across a file of funny letters he got when he was doing so. Here they are, complete with grammatical idiosyncracies (the spelling, shockingly enough, was quite good):

Why does a peanut butter and jelly sandwich always fall on the sticky side?
Lindsay, 4

How do you make a baby and where do they come from? I want to know do they come from salmon? because my mommy ate salmon and now she’s going to have baby.
Sincerely,
Kelly
P.S. My mom won’t tell me so she told me to write to you for you could answer it instead of her because she don’t know anything about how to have a baby’s she don’t know where baby’s come from I guess.

Is it true that sheep eat poison ivy? Could that be why wool is itchy?
Sam

What makes you want to suck your thumb? And what makes your teeth stick out? BUT I DON’T DO IT!

[and my personal favorite…]
The other day I asked my mother why she always had to clean the house. She told me that life was messy. I asked her why life was messy and she said that it was because of entropy.
Do you think that you could talk about entropy on [the show]? She said that I have to clean my room because of entropy, too. Maybe all of the kids who watch your program would clean up their rooms more if they knew about entropy.