Several commonly used lead-in methods in junior high school mathematics classroom teaching

First, the new introduction method of warm and solid knowledge

The new teaching method can organically combine the old and new knowledge, so that students can naturally acquire new knowledge from the review of the old knowledge. For example, when talking about the cutting theorem, first review the content and proof of the chord intersection theorem, that is, the product of the length of two straight lines divided by the intersection point in the "circle" is equal. When two chords are moved so that their intersection points are outside the circle, there are three situations. In this way, students can easily understand the secant theorem and the mathematical expressions of inference, and on this basis, guide students to describe the contents of the theorem, and sum up that the similarity of the circular power theorem is that the products of line segments are equal. The difference is that the intersection chord theorem is the inner segment of the intersection point, while the secant theorem infers that both ends of the outer segment coincide with the tangent theorem. In this way, students can find a series of new knowledge from the review of old knowledge and master the proof method of line segment product equality.

Second, the analogy introduction method

When we talk about the nature of similar triangles, we can take the nature of congruent triangles as an example. The corresponding edge, corresponding angle, corresponding line segment and corresponding perimeter of congruent triangles are equal. What about these triangle-like groups? This method enables students to promote the transfer of knowledge and discover new knowledge through analogy.

Third, personally practice the introduction method.

Hands-on practice is to organize students to practice and explore knowledge and discover truth through their own hands and brains. For example, when the sum of the internal angles of a triangle is 180, ask the students to cut the three internal angles of the triangle and put them together. Therefore, it is concluded from practice that the sum of the internal angles of the triangle is 180, so that students can enjoy the joy of discovering the truth.

Fourth, the feedback introduction method

According to the feedback principle of information theory, some questions are put forward to students as soon as the class begins, and the feedback effect of students is affirmed or corrected before the new class is introduced.

For example, in the right triangle exercise class, a representative exercise can be drawn up for students to discuss before class.

Five, the question introduction method

According to the psychological characteristics of middle school students, question-based lead-in method creates some questions, contradictions and suspense, arouses thinking, arouses students' strong interest in learning, and induces students to move from doubt to thinking and from thinking to understanding. For example, a classmate wants to cut a triangle according to a relative's triangular glass plate. Can he take the glass home and cut the same triangle? The students are talking about it. Then, I told my classmates that triangle judgment is needed to solve this problem. Now let's solve this problem-congruent triangles's judgment.

Six, demonstration teaching aid introduction method

The introduction method of demonstration teaching AIDS enables students to master abstract things vividly, concretely, visually and intuitively through demonstration teaching AIDS. For example, when talking about the definition of chord tangent angle, first separate the compass feet, put the vertices on the circle drawn on the blackboard in advance, and let the two sides intersect with the circle to form the circumferential angle ∠BAC. When one side of ∠BAC does not move and the other side AB rotates around vertex A and is tangent to the circle, let students observe the characteristics of this angle, that is, the vertex intersects with one side of the circle and the other side is tangent to the circle. It is different from the angle of a circle because one side of it is the tangent of the circle. This teaching method makes students impressed and easy to understand and remember.

Seven, direct introduction method

It is a way to ask questions to be solved as soon as class begins. For example, when talking about the cutting theorem, first write the content of the theorem on the blackboard, so that students can distinguish what is known and what is proved, and teachers and students can prove it together.

Eight, emphasize the introduction method.

According to the characteristics of middle school students' interest in meaningful things, a way to describe the importance of this lesson or chapter as soon as class begins. For example, triangle is the focus of plane geometry, and circle is the focus of plane geometry. It occupies an important position in the senior high school entrance examination questions and is the basis for further study in the future. Today, we will learn Chapter 7, Circle. In short, there are many ways to introduce mathematics. The key is to create the best classroom atmosphere and environment, fully mobilize the internal positive factors, stimulate curiosity, keep students in a state of mental excitement and concentration, and create favorable conditions for students to accept new knowledge smoothly.