This activity is a GREAT way to reach every ability level in your classroom all in the same lesson. There are four different leveled worksheets which get harder each new level. (with answer keys!) We print them on four different colors. The students begin to work on the first color and can not move on to the next color until they reach a 100% on the color they are on. If they come up and don't get a 100% when they get checked, I circle what is wrong and send them back to try to figure out their own mistake. This allows you to push those students who are at or almost at mastery, while spending extra intervention time with those stuck on the first one. We LOVE using these kinds of activities to fully differentiate our lesson. We have also added some circular review at the bottom of each worksheet to keep old standards that we have already covered fresh in their minds.