Steve Perry writes:
And one of the funniest ever stories in SF came from his daughter, Astrid. She was taking a science fiction class and there was a quiz question: Why did Robert A. Heinlein write Stranger in a Strange Land?
She answered "For the money."
Teacher marked it wrong, she went up to see him. "Why did you mark this wrong?"
Teacher laughed. "Why did you answer it that way?"
She said, "Because he was at my house talking to my dad and I asked him why he wrote it and that's what he said ..."