To help novice mathematicians understand subtraction concepts, offer them visual representations of the operation. Here, they look at sets of circles. For each of the 16 sets there is a given number they are to cross out, writing how many are left in a box. They cross out one, two, three, four, and five circles, and all the totals are single-digit. By counting before and after they cross out the circles, learners are able to see the process in action. Do this with tangible objects, too!