(1) conforms to the purpose and necessity of teaching. Instructors in classroom teaching must carefully design the lead according to the established teaching objectives, and do not add anything irrelevant to teaching, so as not to make the lead separate from the teaching content.

(2) It conforms to the scientific nature of the teaching content itself. The design of lead should start with the teaching content, some are important components of the teaching content, some are necessary supplements to the teaching content, and some have little to do with the content, but they can stimulate students' interest in learning and attract their attention.

(3) Starting from the reality of students, it is enlightening. The design of lead should proceed from the reality of students and take care of their age and personality characteristics.

(4) The courses need manpower, which is novel and interesting. New teaching should pay attention to reviewing the old and learning the new; Attention should be paid to the care before and after teaching, connecting the preceding with the following; Review class should pay attention to analysis, comparison and summary.

(5) The lead is short and pithy. The design of the lead should be short and pithy, and it usually takes two or three minutes to get to the point.

(6) Careful design, various forms and flexible application. When designing the lead-in, we should pay attention to the cross use of various forms, and we can't use one mode of lead-in in every class.