Review subtraction of 2 numbers whose sums would be 18 or less
Point is, whatever it takes to get students actively involved with the reviewing process where they are not bored and effectively reviewing grade level material in order to prepare them for state or quarterly assessments.
Another important point I keep in mind is that I never want this regular math review time to take up and hour of class time. I want it to be quick but effective. This is not instructional time, but time for the students to review material they have already learned.
Therefore it is our job as the teacher to make sure that when we need to utilize a worksheet, we provide the students with one that is as inspiring as can be.