What is a teaching medium?

The term "teaching medium" originally referred only to the teaching machines that appeared in the United States in the 1960s. Nowadays, it refers to "any means of communication used to disseminate knowledge", including printed materials such as textbooks and teaching reference materials, as well as audio-visual aids such as models, pictures, slides, tape recorders, video recorders, movies, and television.

There are many different ways of categorizing the medium of instruction. The Encyclopedia of American Education divides instructional media into four types: (1) printed materials, such as books, magazines, and pamphlets; (2) graphic media, including charts, maps, bulletin board displays, and projectors; (3) photographic media, such as photographs, slides, and films; and (4) electronic media, including audio and video recording equipment. Others have divided instructional media into five categories, as in Teaching and Media by V.S. Gerlach and others, which divides instructional media into (1) physical objects and people, (2) projected visual materials, (3) auditory materials, (4) printed materials, and (5) presentation materials.

We classify teaching media other than textbooks into the following four categories according to the sensory channel in which they act: (1) non-projected visual aids, including blackboards, models, and physical objects; (2) projected visual aids, including slide projectors, projectors, and their auxiliaries; (3) auditory aids, such as tape recorders, playback radios, radios, and so on; and (4) audio-visual aids, including movies, television, and videos, etc. .