Function in high school mathematics is a very important concept, and all chapters of high school mathematics involve function. If you don't understand the concept of function all the time, it may be because you don't understand its basic definition and nature, which leads to difficulties in later learning.

Function refers to the correspondence between two sets, that is, each independent variable corresponds to only one dependent variable. In mathematics, function is a very abstract concept, which needs to be understood and applied through examples and images.

If you find the math teacher's explanation difficult to understand, you can try to learn through other channels, such as finding relevant videos, tutorials, workbooks and so on. In addition, doing more exercises is also helpful, which can deepen the understanding and application of functions.

At the same time, we should also pay attention to establishing a mathematical foundation and understanding various symbols, formulas and concepts in mathematics, which is the basis for understanding high school mathematical concepts such as functions.

Finally, if you really encounter difficulties, you can ask teachers, classmates or parents for help, or you can consider looking for a professional math tutor for one-on-one tutoring.