In daily life, people's communication is mainly based on language, but in fact, in the whole communication process, language communication only accounts for 7%, and most of the communication is carried out through body movements and facial expressions (Zhu Xiaolin, 20 13). In the classroom, if teachers can catch students' nonverbal signals in time, that is, get students' inner thoughts through micro-expressions and body movements, they can adjust teachers' teaching methods and teaching behaviors in time, thus stimulating students' interest in learning, prescribing the right medicine and realizing the effectiveness of their classroom teaching. This paper aims at expounding the application of micro-expression in teaching, so that teachers can practice and apply micro-expression related knowledge in teaching, guide classroom teaching and improve teaching efficiency.

First, the meaning of micro-expression and research status

Micro-expression is a very transient and uncontrollable facial expression when human beings try to suppress or hide their true feelings (Liang Jing et al., 20 13). The duration of micro-expression is only 1/25 seconds to 1/5 seconds, which expresses people's real feelings that they are trying to suppress and hide (Chi WU et al., 20 10).

In 1966, Haggard and Isaacs found a quick and imperceptible facial expression, which is thought to be related to self-defense mechanism and expresses repressed emotions. 1969, ekman and Freeson independently discovered this kind of facial expression, and named it micro-expression (Liang Jing et al., 20 13). Ekman team has also become one of the main forces to study micro-expressions. In addition, the teams of Matsumoto and Shreve in the United States, Porter and Li Kang in Canada, Polikovsky in Japan, Zhao in Finland and Fu Xiaolan in China are conducting micro-expression research. The purpose is to master the characteristics of micro-expressions and how to recognize them. Most of their research is based on psychology (Liang Jing et al., 20 13). The application of micro-expression is mostly in criminal investigation, judicature, lie detection and other fields, but less in teaching.

At present, most of the documents explaining nonverbal behavior in class are mainly based on body language, paying more attention to teachers' teaching attitude and paying little attention to students' body language, let alone micro-expressions. With the reform of the new curriculum standards, teachers and students began to change the traditional views on teaching and teachers and students. Teachers are no longer the leaders of the classroom, and teachers are no longer just the imparting of knowledge and experience in the classroom. Students began to become the main body of the classroom, and teachers began to pay attention to students' emotions and attitudes when imparting knowledge. So what are the intangible psychological languages such as emotions and attitudes that need to be detected? Any special signals?

Micro-expression is closely related to the process of emotional information processing in human beings, but can people realize that they have micro-expression? Ekman believes that people are unconscious of their own micro-expressions (Liang Jing et al., 20 13). Researchers have not yet reached an understanding of the upper limit of the duration of micro-expressions. Ekman usually thinks that the duration of micro-expressions should not exceed 1/5s, but he sometimes takes 1/4s as the upper limit of the duration. Frank thinks that the duration of micro-expression should be less than 1/2s. From the above research, we can see that expression is an important nonverbal behavior of human beings to express emotional information, and it can be regarded as a barometer of human psychological activities. This transient facial expression is unconscious and can be detected through careful discovery. If teachers are good at capturing students' micro-expressions in their own classroom teaching and adjust classroom teaching in time, they can achieve a win-win situation with students.

Second, the role of micro-expression in teaching

(A) to help teachers teach students in accordance with their aptitude.

In the new curriculum standard, there is a statement about "the basic idea of the curriculum": "Facing all students and paying attention to the different characteristics and differences of language learners" (Ministry of Education, 20 1 1). There are differences in cognitive development level, interest points, personality and cognitive style of each student. To some extent, teachers' classroom teaching is based on teaching materials, balancing the differences between students and promoting their growth. If the teacher can catch the students' reaction to what they are teaching in time, this reaction is more nonverbal, because the students are afraid of being laughed at if they don't understand, and the teacher can't stop to ask the students about their understanding and mastery of the knowledge points every time. At this time, nonverbal behavior is very important. For example, when students are found frowning, staring at the classroom content and listening to the teacher carefully, students are generally trying to think about the classroom content, and their expressions tell the teacher that the content is somewhat difficult to understand. Then teachers can quickly capture students' micro-expressions, get students' information about knowledge points, adjust their classroom teaching in time and realize the effectiveness of teaching. Students can also actively participate in the classroom through some interesting expressions of teachers, so as to understand, gain and digest knowledge points.

(B) conducive to teacher-student interaction.

Teachers in traditional classrooms always talk a lot, while students always listen with their heads down, as one sentence says: Don't talk like a teacher. This sentence is not a criticism of teachers, but reflects the characteristics of traditional classrooms, that is, many teachers sing monologues in class, control the speaking time and deprive students of the opportunity to speak. In the classroom where teachers are monologues, it is not conducive to students' learning language knowledge and developing learning skills. Because knowledge is not taught by teachers to students, but is constructed in the process of interaction between teachers and students (Nunan,1999; Transfer from the process, 2009). Interaction is the core of communication (Brown,1994; Cited from Cheng, 2009), because it is not only the way to realize learning, but also the purpose of learning (Cheng, 2009). Therefore, the learning process is also a process of teacher-student interaction and information exchange. Traditional teachers only pay attention to their own teaching plans and their implementation, and pay less attention to students' interaction and reaction to the classroom, thus causing the classroom to be lifeless. If teachers pay attention to students' micro-expressions when imparting knowledge and developing students' skills, capture students' reaction information to the classroom, interact with students in time, negotiate ideas, fill the information gap between teachers and students, and realize interaction, they can impart knowledge and develop learning skills in the intense discussion and positive interaction between teachers and students.

(3) It is beneficial for teachers to better manage the classroom and organize classroom discipline.

With the advent of the information age, various convenient electronic products came into being, which greatly enriched people's lives. But students bring these electronic products into the classroom, which disturbs the normal classroom order. Many students start playing mobile phones, listening to MP3 players and playing games when they are not paying attention in class. Normal and orderly classroom is the guarantee to realize classroom teaching objectives. In the process of teaching, if a student chats loudly, the teacher can look at him directly, don't blink, lower his eyelids and stare at him with serious eyes. This micro-expression indicates a kind of warning and deterrence, and students will immediately stop and devote themselves to the class. So as to help teachers manage the classroom effectively, organize classroom discipline and realize the normalization of classroom teaching.

(D) conducive to students' active participation in the classroom

In traditional classroom teaching, many students play a passive role in listening and receiving information, so no matter how stimulated by the teacher, they just don't talk. There are many reasons for this problem, some are caused by personality, some are lack of existing knowledge, some are unfamiliar with the course content and so on. If the teacher can capture some information when asking questions in class, for example, pie mouth is a classic expression that shows no confidence in what he says; Touching your hand subconsciously is a gesture of self-comfort. When you don't fully believe what you say, try to dispel your doubts. The other person's eyebrows are raised and his face is tight, which is a sign of fear. These micro-expressions are telling teachers that students are not confident and uncertain when answering questions. If teachers capture the information sent by these micro-expressions, they should encourage students, give them positive reinforcement and enhance their sense of self-efficacy, so that students can boldly and actively participate in the classroom.

(5) It is beneficial to organize classroom teaching and improve teaching efficiency.

As teachers, we all have the experience that students sometimes get distracted in class. Many teachers blame the students for their own reasons, and think that their eyes are distracted and their thoughts are distracted. But few teachers start from themselves to find out the reasons. For example; In class, when students' eyes are found to be up and down, left and right, or turned to other places, it is mostly because students have lost interest in the teacher's lecture content and have a desire to escape. Therefore, when teachers capture this kind of information, they should quickly adjust the teaching content, change the teaching methods, re-arouse students' interest points, bring their thinking back to the classroom and re-participate in the teacher's classroom. Research shows that when most listeners listen to lectures in a relaxed posture, their legs and arms remain in a natural state, and they do not cross their legs or wrap their arms around their chests. Their mastery of the lecture content is more than 38% higher than that of those who hold their chest cross-legged (Zhu Xiaolin, 20 13), which means that people receive more information in the most natural state than when they are nervous. Therefore, teachers should always pay attention to maintaining a lively and relaxed classroom atmosphere when organizing classroom teaching, so that students can get twice the result with half the effort. Teachers can effectively stimulate students' interest in learning, actively organize classroom teaching and improve teaching efficiency by capturing students' micro-expressions in class and constantly adjusting classroom teaching behaviors and strategies.

Third, the conclusion

Micro-expressions are a group of short-lived words, which can't be controlled by people themselves, but can reflect their real thoughts. Although it is not omnipotent, it can make up for and help teachers' teaching. If teachers can catch students' nonverbal behaviors in time, especially their micro-expressions, and adjust their teaching strategies and behaviors, they can interact well with students and realize effective teaching.

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