Last year my husband spent a week teaching his 8th grade math class how to play "Battleship" and organizing "Battleship" tournaments. That's all they did in class that week. The kicker was that they had to play "Battleship" using Cartesian coordinates.
The games got really intense and after a while accusations of cheating started. These were first made before other teachers. As soon as they heard the complaint the teachers laughed their heads off. The aggrieved parties eventually brought up their complaints in class in front of the accused cheater.
My husband laughed his head off. "The whole point of this week was not to play "Battleship". It was to learn Cartesian coordinates. Y'all were scared of Cartesian coordinates a week ago. You've learned them much more thoroughly than if we had done math problems all week long. Now every single one of you can manipulate them like pros. Even the cheater couldn't cheat unless he first learned Cartesian coordinates!"
My husband says he'll never forget the confounded look on the students' faces as they realized they had been tricked into learning something, especially the accused cheater who was a "problem student".