Last week I posted an overview of what (for me) is the fundamental remediation activity to do with students K-10: race games. This week’s subject is Diffies, an extension of race games, whether they involve big or small whole numbers, fractions (common fractions or mixed numbers), decimals, every number to the right of zero on the number line. The link here is a fresh revision of my how-to instructions for Diffies, the paper-and-pencil extension to hands-on race games. Diffies will remind you of the 2nd half of a race game, the race back down to 0, where students have to take away the amount shown on the dice they roll, working their way down to zero. The graphic below shows a blank diffy (click here for a pdf). Once you get a number in each of the four corners, you put the differences in between, working your way down to zero as in a race game. You keep putting the differences in between the new corners until you work your way down to zero. Game over!
Diffies are typically done by a single student, although a second student could join or help. I like rolling dice to get the numbers in the corners, but you could use Excel to get a number at random from a range you specify.