Tic-tac-toe was Mary's favorite game. Every night she and Daddy would fill a sheet of paper with their matches. Then, one day she suddenly saw how easy it was. In that instant she also knew that Daddy always lost on purpose.
So the next night, she tried to lose, instead. But that turned out to be harder than she expected, because of course Daddy was also trying to lose, so they played to a draw. After two more games, he looked at her, puzzled, and then smiled.
"I think you are ready for checkers, kiddo."