There are many researches and applications in cooperative teaching abroad. The Chinese translation is "joint teaching", "cooperative teaching" and "joint teaching", and the domestic usage is "joint teaching". The traditional definition is the teaching practice mode of "two and/or more than two" teachers implementing collaborative teaching in a classroom at the same time (Bach &: Heck, 2007; Friends & Cook, 2004; Kamens, Susco and. Eliot, 2013; Kororuk, 2017; Hollv, Benin, 2020). Whether it is offline classroom, online classroom or mixed teaching classroom, if the cooperation mode of the two teachers can have a clear division of labor, it will directly enhance students' attention to learning, and at the same time increase teachers' teaching professional ability.

Joint teaching has been practiced for many years. Since 1960s, educators have begun to explore the feasibility of joint teaching (Cook &; Friend, 1995). Over the years, the joint teaching mode has been constantly changing and developing with the background of the times and the development of educational information technology. At present, the "double-qualified classroom" in China is also exploring different cooperative teaching modes, and more related explorations and discussions will be put forward in the future.

The background of the development of joint teaching is the shortage of teachers, which can be traced back to the shortage of contemporary teacher resources in the United States in the 1950s. In order to make full use of the limited teacher manpower and promote the teaching effect, the first wave of joint teaching is advocated (Wu Qingshan, Lin Tianyou,1999; Huang Zhixiong, 2006). However, in the educational reform of the United States from 65438 to 0980, the United States once again attached importance to joint teaching for school reconstruction, especially in the field of special education. Many scholars regarded joint teaching as the main basis for special students to return to ordinary classes (Wu, 2002).

The importance of joint teaching mode comes from No Child Left Behind? Act 200 1 (CNLB for short) and the Law on Individual Education for the Disabled (IDEA for short), and joint teaching is recommended as the best time method (Basso &: McCoy, 2007, p. 3).

Joint teaching mode, many researchers put forward that this mode has different positive effects on teachers' teaching and students' learning, and preliminarily sorted out and shared it (Beninhoff, 2020):

1. Professional growth

2, teaching improvement (Improved Instruction)

3. Differentiated teaching.

4. Teacher visits.

5, Behavior Management (behavior management)

6. Student participation.

7. Support students with unclear learning labels in time.

8. Task time

9. sense of belonging

10, accept diversity.

1 1, high expectations