In this activity, students are divided into groups of 4, and they first must use order of operations to solve expressions independently. They will start with Board A, which has 4 expressions that need solved. Each student in the group will solve one problem. After all 4 students are finished, they will add up their answers. In the middle of the board, there is a sum that the 4 answers should add up to. If students do not get the correct sum, they then work together to find the mistake. The sets get progressively more difficult - some groups may get through them all while others may not.