Literature Review This chapter consists of two sections. Section 2.1 gives brief explanation of teachers#8217; feedback in primary school English class and the concept of cooperative principle. Section 2.2 provides a general literature review related the research topic. 2.1 Basic explanation and theoretical basis 2.1.1 Brief explanation of teachers#8217; feedback in the classroom Teaching and learning are dialectical unity in the process of academic related activities. Impartation of knowledge by teachers in the classroom will not come into existence until the beginning of learning by students，while learning also depends on the teaching. In other words, teaching and learning are supplementary to each other and inseparably connected. Under this circumstance, teacher and student, as two of the most basic elements in teaching and learning，are an integral part of teaching process. However, it is teachers#8217; feedback that serves as the bridge between these two elements. The feedback of teachers is a kind of particular response to the behavior, words or ideas of students in the classroom. It can be divided into two types: vocal and non-vocal feedback. In this research, it mainly focuses on vocal one. Functioned as the mediator between teachers and students, feedback conveys the direct or indirect information of teachers to students, and then relevant judgment and adjustment are made by students according to this feedback. The whole interactive process is an emblem of feedback acting as the bridge between teachers and students. Meanwhile, it also corresponds to the philosophy of a new round of curriculum amendment in which it advocates student-oriented teaching model and attaches great importance on interaction. This research mainly deals with the teachers#8217; feedback in primary school English class. Primary school students are in the stage where their mental characteristics feature instability and immaturity. Their learning behavior would change rapidly under the influence of teachers#8217; feedback because they have not formed a mature judgment mechanism. Carl Ransom Rogers, a humanistic psychologist, held the view that the key to success in teaching lays in the relationship between teachers and students and students#8217; affective factors, rather than in the teaching method. Students, especially primary school students, have a strong sense of dependence on teachers. They respect and admire their teachers and are willing to accept the instruction from teachers. At the same time they have a strong desire for the recognition, acknowledgement, appreciation and encouragement of their teachers, so teachers#8217; feedback has a direct impact on primary school students#8217; learning process. 2.1.2 The Cooperative Principle Cooperative Principle，proposed by Grice，(henceforth abbreviated as CP), is the prerequisite for any conversation to take place. In Grice#8217; original wording(1975), it says as follows：Make your conversational contribution such as required at the stage at which it occurs by the accepted purpose or direction of the talk exchange in which you are engaged. To be more specific, there are four maxims under this general principle: Maxim of Quantity 1) Make your contribution as informative as is required (for the current purposes of the exchange); 2) Do not make your contribution more informative than is required. Maxim of Quality Try to make your contribution one that is true, specially: 1) Do not say what you believe to be false; 2) Do not say that for which you lack adequate evidence. Maxim of Relation Be relevant. Maxim of Manner Be perspicuous. 1) Avoid obscurity of expression; 2) Avoid ambiguity; 3) Be brief (avoid unnecessary prolixity); 4) Be orderly. 2.2 Related studies 2.2.1 Studies on feedback Teachers#8217; feedback forms a vital part in the class and is indispensible in the interaction between teachers and students (Chaudron, 1988). Especially in the second language acquisition class, teachers#8217; feedback is not only a means to evaluate the academic performance of students, but also an integral part in learning a foreign language, as well as plays an important role in the output of language.(Gass Mackey, 2006) Based on the researches carried out in recent decades, it concludes that second language acquisition closely links to affective factors that encompass motivation, self-esteem, confidence, anxiety and so on. As English class is one of the most significant places to acquire the second language, teachers#8217; feedback in it is of great importance in the influence of students#8217; affective factors. Drawing on the experience of existing research findings on psychology and sociology, Krashen (1985) put forward the Affective Filter Hypotheses where it expounds that affective factors exert direct influence on the second language acquisition and filter the input of language. The lower the motivation and confidence of learners are, the higher of anxiety. As a result, the level of filtration to learning material is higher, that means low learning efficiency. On the contrary, the intake of material is higher. Therefore, it is teachers#8217; responsibility to stimulate learning motivation of students in the classroom as well as to improve their self-confidence and minimize the anxiety level in order to better learn a language. From different aspects like anxiety, motivation, confidence and so on, Ellis (1994) also tried to explain the importance of affective factors in the second language acquisition. Furthermore, Gardener (1991) proposed that the learning environment in the classroom, in return, will affect the affective factors of learners and then the input of language. Therefore, rational and efficient feedback helps to advance the initiative and enthusiasm of students and encourage engagement in the classroom. So it has positive effect on consolidation of learning content and correction of students#8217; mistakes in learning. Nevertheless, improper and untimely feedback tends to frustrate the confidence and learning motivation of students. As a result, the involvement in class of students is badly affected. What is worse is that it is a chain reaction because it will do harm to the learning process in the future. To sum up, teachers#8217; feedback plays a vital role in the second language acquisition, however, most researches in home and abroad on teachers#8217; feedback center on the type and function of feedback. There are few researches discussing how to apply these kinds of feedback effectively from the perspective of linguistic. 2.2.2 Studies on feedback from the perspective of the Cooperative Principle Recent years, some studies have been conducted to discuss feedback from the perspective of the Cooperative Principle. According to those previous studies, we will find that some scholars stand the point that Cooperative Principle gives a solid theory basis and inspiration in the use of feedback in English class. In the paper The Application of Cooperative Principle in Teachers#8217; Feedback in The Middle School English Class (Gong Zhuolu Yu Jiayin), authors consider that Maxim of Quantity requires teachers#8217; feedback should be concise and clear. Maxim of Quality the fairness and pertinent of the feedback. Maxim of Relation the correlated feedback and Maxim of Manner the valuable feedback. While some scholars believe that in order to achieve the functions of feedback, teachers will violate the cooperative principle unconsciously or deliberately. The violation of CP can reduce the distance between teachers and students and make the contents easier and clearer to be grasped（Zhang Mengjiao 2016）. Under the influence of education reform and the increasing awareness of the importance of appropriate teachers#8217; feedback in the class, the research on this field has been gaining more and more popularity among teachers and scholars. Based on previous researches, some of them have indicated that the adherence of CP in giving feedback will have positive effect, while others think that the violation of CP also has its advantages. So this research will make a deep analysis on the teachers#8217; feedback in primary school English class and hope to bring some recommendations or suggestions to improve the application of feedback.