1, knowledge difference There are many knowledge points in junior high school mathematics, such as four propositions and function concepts. Therefore, when teaching new knowledge, teachers should guide students to contact with old knowledge, review and distinguish old knowledge, and pay special attention to analyzing and comparing those knowledge that are easy to make mistakes and confuse, so as to achieve the effect of reviewing old knowledge and learning new knowledge. For example, when learning the solution of quadratic inequality in one variable, teachers should guide students to review the knowledge of quadratic equations and quadratic functions they learned in junior high school, and make necessary preparations for learning the solution of quadratic inequality in one variable, such as the discriminant of roots, the formula for finding roots, the relationship between roots and coefficients (that is, "Vieta theorem"), and the images of quadratic functions. Junior high school mathematics knowledge is little, shallow, easy and narrow. High school mathematics knowledge is extensive, which will promote and extend junior high school mathematics knowledge and improve junior high school mathematics knowledge. For example, the concept of angle in junior high school is only within the range of "0- 180", and there are actually 720 degrees and "negative 300 degrees". Therefore, high school will expand the concept of angle to any angle, which can represent all angles, including positive and negative. Another example is: when studying solid geometry in high school, you will find the volume and surface area of some geometric entities in three-dimensional space; In order to solve the problems such as the number of queuing methods, we will also learn the knowledge of "permutation and combination". For example: (1) A line of three people (=6) There are several queuing methods; (2) How many times do four people play table tennis doubles? (A: =3 kinds) Senior high schools will learn mathematical methods to count these arrangements. The square root of a negative number in junior high school is meaningless, but it is stipulated in senior high school that =- 1 makes the square root of-1 i. That is to say, the concept of number can be extended to the range of complex numbers. These knowledge students will learn step by step in the future study.