This paper investigates some studen

This paper investigates some students who are going to become middle school mathematics teachers in eight American universities, and concludes that teachers' professional knowledge can be analyzed from seven aspects: the essential characteristics of concepts: different representations of concepts; different approaches to concepts; the influence of concepts; basic examples of concepts; understanding of concepts; and related mathematical knowledge. The research points out that the function knowledge level of these respondents is weak, and they do not have a comprehensive and perfect understanding of the mathematics course to be taught. From the survey, it can be seen that students who are not majoring in mathematics have a lot of problems in understanding the concept of function. The understanding is simple and superficial. They do not grasp the essence of the concept of function properly. What can give a correct description of the function is directly proportional to the level of mathematics they have learned. A survey of 62 sophomores and juniors majoring in Mathematics in American universities shows that only 40% of them are proficient in function definition, 22% of them are not proficient in function definition, 24% of them are proficient in function definition, 14% of them are proficient in function definition, and 22% of them are not proficient in function definition. This paper points out that the students can not fully understand the concept of function, and explains the reasons for these difficulties from the theoretical point of view, and designs the educational treatment method, that is, in the teaching of function concept, using isetl language with the help of computer programming, after two months of learning, let the students answer the definition of function again, the result shows that after having the experience of computer programming, The proportion of students who answered the definition of function as proficient decreased, while the proportion of more proficient students increased, and the proportion of students who did not understand it also decreased. It is worth noting that before the education and treatment, 48 students who thought that function was given realized that function learning is a process, and can construct functions to solve practical problems.