1. In order to complete the established teaching tasks, which one or several kinds of rich and varied teaching media combination is the most appropriate and effective? What is the basis of its choice? I think the basis for choosing teaching media is: 1. According to the teaching purpose, every learning task and every class has a certain teaching purpose, such as making students know a certain concept, understand a certain law, master a certain skill and form a certain attitude. In order to achieve different teaching purposes, different media are often used to convey teaching information. Taking foreign language teaching as an example, letting students know all kinds of grammar rules and enabling students to have a dialogue on a certain topic are two different teaching goals. The former is mostly explained by teachers, supplemented by blackboard writing or projection materials, so that students can form clear grammar rules in orderly content arrangement; The latter often uses role-playing, supplemented by slides or video materials, so that students can master correct language skills under the communicative conditions of situational integration. But in order to correct students' foreign language pronunciation, it is best to use audio and video recording. 2. According to teaching objectives: Teaching objectives are the basis for guiding and controlling the operation of teaching activities. In the process of selecting media, we must consider the needs of teaching objectives. For example, when students are required to know or understand some specific concepts or principles, we can consider choosing different media to convey different information. For the cultivation of different goals in cognitive field, emotional field and motor skill field, it is more necessary to consider the differences of media. 3. According to the different nature of each subject, the suitable teaching media will be different; Different chapters of the same subject have different contents and different requirements for teaching media. For example, in Chinese teaching, it is best to reshape the image by speaking and reading narratives with literary characteristics. Therefore, students should feel that they are there through the media that can provide some scenes, so as to arouse the imagination of the characters, scenes and plots in the text and deepen their understanding and experience. For example, the concepts and principles of mathematics, physics and other disciplines are abstract and can only be understood through a series of complex thinking processes such as analysis, comparison and synthesis. Therefore, we should choose the appropriate teaching media according to the teaching content in order to achieve high classroom efficiency. In addition to the above two aspects, we should also comprehensively consider the requirements of objectives and contents, the characteristics of learners, teaching environment and possible constraints. 4. According to the teaching target: learners of different ages have different abilities to accept the media. For example, for primary school students, it is not easy to concentrate for a long time, and slides, movies and videos can be used to express information vividly. 5. According to the teaching conditions: Whether a certain media can be selected in teaching depends on the specific local environment at that time, and what constraints should be considered, such as school funding guarantee, equipment quantity, power supply, school management system, leaders' consciousness and so on. Second, the method of teaching media selection In order to guide front-line teachers to choose media more reasonably in the teaching process, people have also accumulated a series of media selection methods. Mainly: 1, question table: The question table lists a series of questions that the media selector needs to answer. By answering these questions one by one, the media suitable for a certain teaching situation can be clearly found. 2. Matrix: Matrix is usually arranged in two dimensions, such as taking teaching methods as one dimension, the technical level of media as another dimension, and then taking typical media suitable for use as parameters to describe the relationship between them. 3. Arithmetic: In the process of determining which teaching media to use, some teachers will quantitatively compare the function of alternative media with the cost they need to pay, so as to obtain the benefit index of different media, and then determine the media suitable for specific teaching situations. This media selection method is usually called an algorithm. The calculation of cost is only a relative concept. For example, when comparing the cost of slides and pictures displayed on the computer, it should be based on the conditions of the school. If there are no computers in the school or the number of computers is limited, the cost of making a slide may be lower, but after computers or networks have become very popular, the cost of finding a picture through the network may be much lower. 4. Flowchart: In the process of teaching media selection, the selection process is decomposed into a series of steps arranged in sequence, each step provides a question, which is presented in the form of a block diagram, and the selector answers "Yes" or "No", and then logically introduces different branches. According to the questions answered, we can determine the media that is most suitable for the specific teaching situation. This media selection method is generally called a flowchart.