(A) the position and role of this section in the textbook. Congruent triangles's research is actually the first step to study the relationship between two closed figures in plane geometry. This is the simplest and most common relationship between two triangles. The section "Exploring the conditions of congruence of triangles" is learned by students after they know triangles, congruence graphs and congruent triangles. It is not only the extension and expansion of the previous knowledge, but also the basis for the subsequent study and exploration of shape similarity conditions, and it is also an important basis for explaining the equality of line segments and angles. So the knowledge in this lesson plays a connecting role. At the same time, the recognition method of "edges and corners" is regarded as one of the five basic facts in the textbook of Jiangsu Education Edition, which shows the important role of this section in students' learning geometric reasoning. (II) Teaching Objectives In the teaching of this course, students should not only learn the method of identifying the "edges and corners" in congruent triangles, but also master the method of studying problems and initially understand the mathematical ideas of classified discussion. At the same time, let students feel that mathematics comes from life and serves the basic facts of life, thus stimulating students' interest in learning mathematics. To this end, I set the following teaching objectives: (1) Experience the process of exploring congruence conditions of triangles, experience the method of analyzing problems, and accumulate experience in mathematical activities. (2) Mastering the discrimination method of triangle congruence, and using these conditions to judge whether two triangles are congruent, and solving some simple practical problems. (3) Cultivate students' spirit of exploration, unity and cooperation. (3) Teaching materials focus on difficult points. Because this class is the first time to explore the conditions of triangle congruence, I have established the identification method of "exploring the number of necessary conditions in congruent triangles and exploring the edges and corners" as the teaching focus, while the discovery process and the analysis of edges and corners are the teaching difficulties. At the same time, I will use the methods of students' hands-on operation, cooperative inquiry, media demonstration, and infiltration of classified discussion in the teaching of mathematical thinking methods to highlight key points and break through difficulties. (4) Prepare teaching tools and teaching AIDS: related multimedia courseware; Learning tools: scissors, paper, ruler. Homework paper with relevant pictures. Second, the choice of teaching methods and the guidance of learning methods This lesson is mainly about the discovery of the basic fact of "margin". Therefore, I will try my best to provide students with the time and space of "learning by doing" in classroom teaching, so that students can study in groups, and in the process of "doing", the mathematical thinking method of classified discussion will be infiltrated imperceptibly, and the principle of "teaching is for not teaching" will be followed, so that students can find their own methods, laws and rules while enjoying knowledge. Third, the teaching process (1) Creating scenes to stimulate the desire for knowledge First of all, I will show a practical problem: Problem: Pippi Company has received a batch of triangle frame processing tasks, and the customer's requirement is that all triangles must be congruent. In order to make the products pass customs smoothly, the quality inspection department put forward a clear requirement: check whether all three sides and three angles of the triangle are equal one by one. Mao Mao of the technical department raised a question: Is it ok to check the six data of three sides and three corners respectively? But in order to improve our efficiency, can we find a more optimized method and only measure one data? How about two? ..... Then, the teacher asked: Mao Mao put forward such an idea, can the students overcome this problem with Mao Mao? The purpose of this design is not only to explain the main problems to be studied and studied in this course, but also to stimulate students' desire for knowledge and exploration and pave the way for the teaching of this course. (2) Guiding activities reveal that the essence of mathematics teaching in the process of knowledge generation is the teaching of mathematics activities. To this end, I designed the following series of activities in this class, aiming to let students reveal the process of knowledge generation through hands-on operation and cooperative inquiry. Activity 1: Ask the students to draw a picture or illustrate that there is only one data, that is, an edge or an angle, and it is impossible to judge the congruence of two triangles. Activity 2: Ask students to discuss measuring two data. Let the students analyze several situations first: edge, angle and angle. Then each group will explore for themselves. Students can also give counterexamples or draw pictures to illustrate. Activity 3: On the basis that two conditions cannot be determined, only one more condition can be added. Let the students discuss several situations first, and the teacher is inspiring students to think in an orderly way to avoid missing solutions.