When I was in school, one of the economic theories I heard was that if you gave everyone in the class a dollar, by the end of the day, some people would have lots of money, some the same dollar, and some no money. With children, you get to see that in practice.
Me: "CC, why are you putting away the bathroom towels? That's B's job."
CC: "He said he'd like to play instead, so he's paying me $1 if I'll put them all away."
And I decided to keep my mouth shut because all I wanted was for the towels to be folded and put away by someone other than me.