Random thought that I'm not sure is even a good thought. Tried the number pizza man game, and one mechanic which I thought may be interesting is if the distribution of values in the pizza boxes changes as time goes on. Rather than maybe skipping ahead after a while if the student doesn't get it, slowly change the randomization to include more and more, and then perhaps only exclusively, the right answer. This would allow a kid to still "get it," while still engaging them in the game mechanic.