The game is simple: one student works while the other waits. In the version of the game above, one student is hitting the pad while the other holds a plank position. While there are many things to be gleaned from this game, my favorite is watching students go from being completely still (plank pose) to springing into action (hitting the bag).
The variations are endless. One student can hold a horse stance while the other does jumping jacks. One student can hold a crane stance while the other does their form. You can vary up the intervals, too. Sometimes it can be a fixed interval that the students switch at (in the video above, 30 seconds). Sometimes you can make them switch after a certain number of reps (30 jumping jacks, maybe). Sometimes you can make them switch whenever one of them gets exhausted.
Play with it.