A new lecture on old topics. In the teaching process, some examples are often explained once and put aside. Over time, it has caused students to despise the old questions and blindly seek perfection, thus entering the sea of questions. In fact, a good example is like a masterpiece. We can talk about it again and think it over. Especially in the review stage of teaching, you can extend its changes, expand students' thinking, dig out new ideas from old questions, make people think and leave a much deeper impression on students. Sometimes, what students come up with by themselves will surprise teachers, which makes us have to sigh the students' intelligence and wisdom, and at the same time, we have chosen a good topic for ourselves, which is memorable.

Make a mountain out of a molehill Some examples are simple and easy to prove, but they are rich in connotation. If we can dig deep and make good changes, we can often draw inferences from others and achieve the effect of substituting examples for classes, that is, we often say that we can know a class or even a piece by doing a problem. Why not give such an example to review?

Tell me more questions. Some examples are similar in graphic structure, problem background and solution, and even some problems have the same conditions, but the conclusions are different, so many problems should be discussed. It can make students feel that many problems can be solved with the help of the same core knowledge as long as the connotation and extension of the problem are thoroughly excavated and then applied flexibly.