Interesting lead-in is indispensable for students in junior high school in that they are more willing to devote themselves to things they like。 Because of their poor self-control, when they attend a class, students are often in an "absent-minded" state, which requires teachers to quickly arouse their attention at the very beginning of a class。 Junior high school education requires students to make better use of textbooks, including more vocabulary and English grammar skills, which makes students feel difficult to learn English well。 So, teachers must take students as the center in teaching so that they can learn about students’ learning needs and meet students’ requests。 Teachers should design an introduction flexibly according to different principles and methods of lead-in。 

2。 Literature Review 

2。1 Findings of previous researches文献综述

     At abroad, in the 1970's, Turney said that at the beginning of a class, attracting students' attention and stimulating their desire for knowledge is of great value (Turney 167) 。 In the 1990's, James M。 Cooper held the view that the final goal of lead-in is stimulating students' attention and desire to participate in the class activities (Cooper 24)。 Willis insisted that lead-in should be pided into three tasks: pre-task, while-task and post-task (Willis 26)。 Richard I。 Arends put forward that as the first step of a lesson, lead-in plays an important role in attracting students' interest and stimulating students’ desire for new knowledge (Arends 1) 。 In the 2000's, Robert Slavin concluded that teachers should arouse students’ curiosity and stimulate thinking in learning new content by setting lead-in questions (Slavin 223) 。