Classification discussion has always been an important idea in junior high school mathematics. After more than two semesters of training, according to my experience, I summed up several common routines.

1. When doing a geometry problem, if there is no drawing in the problem, we need to think for ourselves and then discuss it in categories. We don't need to pay attention to details when drawing, we just need to draw a general meaning, which is to be clearly distinguished from other types. Secondly, classification is also very important when doing these questions here. After translation classification, the problem is done quickly and the thinking can be sorted out clearly. For example, when doing the angle problem in a triangle, for example, wait a minute, we can distinguish it according to the vertex angle, because the vertex angle is more obvious in the picture, because there is only one, like those waist angles and bottom angles, and two are more difficult to determine. Although this is a good classification method, we should find the right one according to the question type.

2. In Grade One, we often encounter some headache, moving point problems, in which the idea of classified discussion is extremely important. In this kind of problems, the moving point is often in a line segment, a straight line or a closed geometric figure. Some endpoints in the graph are good classification critical points. Critical point is extremely important in the fixed point problem, and it can only be classified if it is found. This kind of problem, I boil down to the problem of using your head.

In fact, classified discussion is comprehensive thinking. We should find out all the possibilities, classify them one by one, and then draw some conclusions. This is actually a very good idea, and it is a good way to deal with both study and life. The above is my personal opinion.