You're teaching the "count on" strategy to solve subtraction problems, and what do your kids do? They use it to solve ridiculously hard problems, like 12 - 5 (can you imagine? "5, 6, 7, 8, 9, 10, 11, 12.... okay, how many was that?)
This game is designed for students to practice deciding if a problem should be solved using the "count up" strategy and then solving it when it does. Please not, I only teach the "count up" subtraction strategy when the numbers are 1, 2 or 3 apart. After that, the technique leads to errors and is inefficient.
The game is easy to teach: there are 3 "mice" on the board and 1 "cat." The player who is the cat picks two cards, looks at them and decides if either or both use the "count up" strategy. If they do, they player can move his "cat" into an adjacent space with that number in it. The "mouse" player can do the same thing, but only gets one card per turn (this is because cats are much faster than mice...) The goal is for the mice to get to the "safety zone" and the cat to catch the mice.
If you like this, look at my other games and puzzles for your kids!