This lesson is the content of the second section of Chapter 12 of the eighth grade mathematics of People's Education Press, which mainly explores the conditions of triangle congruence and proves it with congruent triangles. I taught the first lesson: the judgment method of triangle congruence (SSS) 1, which is the basis of the later judgment method and the key and difficult point of this chapter. The textbook seems simple. After careful study, it is found that it is difficult for eighth-grade students to succeed if they don't handle it well. But also plays a key role in students' future study of geometry. So in this class, I carefully designed the link from determining a triangle to getting the judgment method of triangle congruence, so that students can operate, make bold guesses, practice and verify each other, which solved the problem well and successfully completed the task of this class, as follows.

First, I prepare lessons carefully, the teaching design is comprehensive, and the content is life-oriented. First of all, I asked students to cut two triangles to make them congruent, which not only reviewed congruent triangles's definition, but also made a good transition to the problem of determining what conditions are needed for triangles. Then, I introduced a new lesson with "matching glass", which aroused students' curiosity and made them feel that knowledge came from real life, thus designing an inquiry question: how to draw a triangle and be congruent with the cut triangle? What do you think is the minimum requirement? Stimulate students' thirst for knowledge, fully let students freely exchange and discuss, make bold guesses, guide students to find problems in class, and solve problems through hands-on operation and discussion.

Second, focus on the situation covered by "one condition" and "two conditions" and the reasons why they cannot be formed, so that students can find out for themselves (or be guided by teachers). Let the students practice and form cognition through this section.

Thirdly, I carefully designed a demonstration to judge the "side by side" theorem, forming an intuitive impression. Before class, I prepared six sticks of equal length, and asked the students to put them into two triangles and guess whether they are equal. After that, the conclusion of speculation and the conclusion of need are verified by coincidence.

Fourth, draw a triangle with a ruler and a hand-cut triangle to guide students to try drawing and let them find the existing problems. Finally, the correct drawing method is given, and students' drawing is taken as the center to carry out inquiry activities, so that students can experience it personally, obtain "SSS" conditions from practice, and cultivate their ability to explore, discover and summarize laws.

This course has achieved some success in breaking through difficulties, stimulating students' interest and hands-on operation. However, in the future teaching, there are also some things worth thinking about: (1) let students prepare learning tools (such as paper, scissors, compasses, etc.). ) in advance, and when grouping, the advantages and disadvantages complement each other, making people learn something. (2) Pay more attention to students in teaching. After learning new knowledge, although most students have mastered it, there are still a few underachievers who don't understand it. (3) List more cases among students, such as completing damaged triangles.

In short, in mathematics classroom teaching, teachers should always pay attention to providing students with reference opportunities, reflecting students' dominant position, giving full play to students' subjective initiative, and providing students with a platform of "learning by doing" as much as possible, so that students can actively explore new knowledge, expand their knowledge structure and develop their abilities with the help of their existing knowledge and methods in the process of learning by doing, so that classroom teaching can truly serve the development of students. This is the direction of my future efforts.