There is no essential difference between the teaching activities of mentally retarded children and those of normal students, so there are many common teaching principles, such as the principle of all-round development of education, the principle of inspiration, the principle of unity of science and thought, the principle of teaching students in accordance with their aptitude, the principle of step by step, the principle of feedback, etc. These are the basic principles that all teachers must abide by in teaching. However, after all, children with mental retardation have physical and mental development obstacles, which will inevitably affect their learning process and effect. Therefore, there are some special principles that should be observed in the education and teaching of mentally retarded children.

(A) scientific principles

Teaching should be scientific and accurate, and scientific principle is a basic teaching principle to ensure the scientificity and effectiveness of teaching. Although this principle is the first principle that all teaching activities must abide by, the scientific principle of teaching mentally retarded children is particularly important. Specifically, the scientific principles of teaching children with mental retardation mainly include three aspects: first, the content chosen by the teaching designer must be scientific, that is, the knowledge and skills taught by the teacher conform to the scientific spirit. Secondly, the organizational form, presentation mode, teaching sequence and teaching method of educational content are scientific, that is, the teaching method conforms to the discipline teaching law and the learning characteristics of mentally retarded children. Thirdly, the contents and methods of teaching evaluation should be scientific.

(2) Functional principle

Functional principle is a special teaching principle based on the physical and mental obstacles of mentally retarded children, the amount of educational restrictions and the basic needs of participating in social life. Functional principle refers to teaching the most important knowledge and skills necessary to adapt to environmental life to children with mental retardation and helping them to apply them in a specific environment, so as to form functional knowledge and skills needed to participate in social life according to the environment. The principle of functional teaching requires teachers to pay attention to the application of knowledge and skills in a specific environment, including the application mode and effect, when considering the logic of teaching subject knowledge. Functional principle is more suitable for children with severe mental retardation, multiple mental retardation or older mental retardation to develop social skills.

(3) the principle of compensation

Children with mental retardation affect their study because of physical and mental obstacles. The principle of compensation is a special teaching principle based on the need of defect compensation for children with mental retardation. The principle of compensation refers to that teachers provide professional education and training with special teaching contents in view of the cognitive, language, memory, behavior and emotional defects of mentally retarded children in the teaching process. For example, the brain injury of children with mental retardation makes them particularly prone to fatigue in the learning process, unable to study for a long time and unable to concentrate; Low social participation and poor cognitive level lead to their poor ideas, and it is difficult to establish a connection between ideas and things, so it is difficult to understand what they have learned; Language barriers lead them to misunderstand, unable to express their ideas, and poor information communication in turn affects their better understanding of what they have learned: hand-eye coordination and hand control obstacles lead them to learn operational skills, especially writing difficulties; Poor observation, resolution and memory make it difficult for them to advance their studies. In view of this, teachers must consider students' obstacles and compensation needs in teaching. In addition to teaching students the selected knowledge and skills, we should also provide timely compensatory training by using the teaching process to promote the all-round development of children with mental retardation.

(D) the principle of intuition

Intuition principle is put forward in view of the low abstract thinking ability of mentally retarded children. The principle of intuition means that teachers help students to deepen their feelings and understanding of teaching content with the help of intuitive teaching AIDS, so that students can better master knowledge and skills. The principle of intuitive teaching conforms to the cognitive law of learners, so it has high application value for all learners. Many contents in school education cannot be directly felt and observed in daily life, so when learning such contents, we must rely on the existing representations and concepts in learners' brains to make reasonable reasoning and imagination. If learners lack representation in their minds and have poor logical thinking ability, it is likely that learners will not understand what they have learned. Due to cognitive impairment, lack of social experience and low thinking ability, children with mental retardation often show problems such as lack of representation, limited logical thinking and difficulty in reasoning. Therefore, the principle of intuitive teaching is to enrich students' direct experience and perceptual knowledge through intuitive teaching AIDS, language, movements and expressions, so as to serve them in learning knowledge, forming concepts and developing intelligence. Therefore, the principle of intuitive teaching can help students understand the learning content, which is of great value to children with mental retardation. However, it is worth noting that the application of this principle in teaching should fully consider the teaching content, teaching objectives, teaching tasks and students' existing knowledge structure, and carefully choose intuitive teaching AIDS.

(5) the principle of small steps

The principle of small steps is put forward according to the learning disabilities of mentally retarded children, such as difficulty in concentration, poor understanding and poor memory. The principle of small steps and quick running means that teachers should provide appropriate teaching quantity according to the cognitive characteristics and learning ability of mentally retarded children in teaching. According to the psychological characteristics and learning characteristics of mentally retarded children, the state stipulates that each class in mentally retarded schools is 35 minutes. However, the learning potential of mentally retarded children with different disabilities, different ages, different interests and different habits is different. Teachers should arrange teaching time and teaching quantity reasonably according to teaching content, students' obstacles, characteristics of attention and memory and students' interest in learning. For example, in teaching, teachers need to set the content as several teaching tasks and teaching links that are easy for students to understand and operate, so as to guide students to learn and consolidate their knowledge and skills in specific activities. In addition, teachers should arrange teaching weights according to each child's acceptance ability. Especially for the difficulties and key points in teaching, we must adhere to the principle of low starting point and small steps, and design the difficulty and slope of teaching according to children's ability level to promote children's learning.

(6) Individualization principle

Individualization principle is a teaching principle that is put forward in view of the great individual differences of mentally retarded children and the unique educational needs of most mentally retarded children. Individualized teaching principle refers to the individual differences (characteristics) of mentally retarded children, designs the basic learning volume for each child, and then adopts corresponding methods to promote their development. The core of the principle of individuation is that teachers should fully consider the different learning abilities, learning foundations and learning needs of different children when designing teaching activities. Because of the different obstacles, cognitive development, learning ability and emotional state of mentally retarded children, it is very difficult to give full consideration to all children's educational interests in the same classroom. Therefore, the teaching of mentally retarded children must implement the principle of individualization, which is reflected in all aspects of teaching objectives, teaching process, practice and evaluation. Therefore, the principle of individualization actually includes the individualization of teaching contents, requirements, means and methods.

(7) the principle of merger

The principle of consolidation, also known as the principle of full practice, refers to that teachers guide students to internalize and maintain their knowledge and skills for a long time through effective memory strategies and repeated exercises on the basis of fully understanding what they have learned in the teaching process, and accurately reproduce and use them when necessary. This principle is a teaching principle based on the characteristics of children with mental retardation, such as slow memory speed, fast forgetting speed and poor use of effective memory strategies. Memory disorder and bad memory strategies lead to low learning efficiency of mentally retarded children. Teachers must strengthen consolidation exercises to prevent students from forgetting what they have learned.