First-line class and second-line class are two common concepts in the field of education.

First-class: First-class is an ordinary class in the general sense, which consists of parallel classes with a large number of students and relatively limited teacher resources. The teaching content is relatively basic, mainly focusing on the cultivation of students' comprehensive quality.

Second-tier classes: Second-tier classes refer to special classes, such as super-long classes and experimental classes, which are usually composed of students with special talents or hobbies. The teaching contents and methods of these classes are more professional than those of the first-line classes, and they pay more attention to the cultivation and development of students' specific talents.