Diffy is great for practicing subtraction, but it also requires students to think logically and identify patterns. It can be played with integers, negative numbers, fractions, decimals, and money, but I think it is most fun with whole numbers. It’s great for kids, but adults enjoy playing, too.
Begin by writing four different numbers into the four circles on each of the outer corners. Fill in the outer squares by subtracting the smaller number from the larger number on each corner. Continue working toward the center, subtracting the corners. What patterns do you see? Can you get to the middle without a difference of zero?
Here is a completed one. As you can see, the player (who was me) did not win because the circles furthest from the center all came up zero. Can you win? Can your students? And perhaps more importantly, what will your students learn about number relationships while they are trying?