Audio-visual Instruction, the use of teaching materials and techniques that do not depend mainly upon the printed word to convey meaning. It is also known as instructional media and works through sight and sound. Such materials—for example, still and motion pictures, videotapes, recordings, museum exhibits, and multimedia computer software (software emphasizing images and sound)—are used to supplement textbooks. A person’s ability to remember what he or she learns can increase vastly through a combination of seeing and hearing information. A lecture as such is not audio-visual instruction, but becomes so when the speaker uses slides, exhibits, or similar aids. A wide variety of audio-visual materials are used by the teachers in daily instruction. Audio-visual materials ranging from the simple devices like chalkboards to complicated digital multimedia systems are used in schools, in religious education, in the home, and in training programs in government, the armed forces, and business and industry.
The computer is gradually becoming a more powerful tool for educational purposes. Initially, the use of computers was limited to assisting with regular learning programs, such as mathematics exercises, but today its sophistication levels have increased significantly. Instructional packages can be created by a multimedia computer in the present day by blending text, pictures, moving images, and sound. One of the most popular multimedia applications currently, is PowerPoint. Moreover, the World Wide Web makes a vast amount of visual and audio information available to students in a matter of seconds.
Visual materials like pictures, maps, charts, models, or actual objects being discussed are primarily for seeing. Images projected onto the screens or displayed on computers are also visual materials. Devices like chalkboards, dry-erase boards, and flip charts are still the most popular visual aids upon which the instructor can write information, even with the increased capacity of computers to assist in education.
Smooth, dark boards made of slate, glass, or wood, the chalkboards are probably the most extensively used visual aid. Chalk or crayon can be used easily to write or draw on the boards. Large protractors to measure angles and devices to draw the five lines of a musical staff are the other kind of accessories used with chalkboards. Cardboard-cut patterns can also be used to trace outlines on the chalkboard.
A user can write with special felt markers on a dry-erase board, which is a steel surface coated with white enamel. There are some dry-erase boards that include a scanning device that scans what is written on the board and generates paper copies as well.
Large pads of paper mounted on a frame are called flip charts. The pad is used by the user to write information during a presentation; he or she can also prepare it in advance to display while speaking. It is also possible to enlarge material on a regular sheet of paper by a special machine, for use on a flip chart. Flip charts are relatively small and portable when compared to most chalkboards and dry-erase boards. The flip chart also helps an instructor in displaying individual sheets of paper around the room so that the group can refer to important points presented earlier in the lesson. Flip charts are frequently used by business and industrial trainers.
Projection devices are used by many teachers to supplement their lessons with material that can be projected on to a screen. Both solid and transparent objects can be displayed on the projectors. Opaque projectors, overhead projectors, filmstrip and slide projectors, and liquid crystal display projectors are the most widely used projectors.Materials that cannot let light through them can be seen through the opaque projectors. An enlarged image of a book, document, or small object can be displayed on a screen by these projectors, When light from the projector lamp shines on the object, a tilted mirror reflects an image of the object and enlarges it through a lens on to a screen.
Transparencies’ on a screen are projected by the overhead projectors. The transparency, which is a clear plastic sheet with material printed on it, is placed on a clear flat surface over a projector lamp. The image is reflected by a mirror through a lens on to the screen. Several methods like drawing or writing on a clear plastic sheet can be used to make transparencies. Photocopying machines, computer printers, and other devices can also be used to make them.Images on to a screen are also projected by filmstrip projectors and slide projectors. A strip of 35-millimeter film with a series of related still images that are displayed by a projector makes a filmstrip. There are a number of filmstrip projectors that have built-in tape players to provide sound to accompany the images. Individual transparent photographs called slides can be shown through a 35-millimeter slide projector. Slides are arranged in a tray from which they individually drop between a light and the lens that projects them. Filmstrip and slide projectors have been replaced by computers and other devices in many classrooms.
Using a substance called liquid crystal that changes color when an electric charge is applied to it, the liquid crystal display (LCD) projector picks up information. An LCD panel can pick up and display an image of what appears on the computer screen when attached to a computer. LCD projectors are used by teachers and others to present computer images, as well as play video clips and display computerized slide presentations. LCD projectors can also present information from the World Wide Web and can project images from television systems.Using a special type of electronic circuit that contains up to 2 million tiny pivoting mirrors, the digital light processing (DLP) projectors can create images. DLP projectors can also display computer images just like the LCD projectors.
Audio materials are primarily for hearing and include audio cassette tapes, audio compact discs (CD's), and the machines on which they are played. These materials are frequently used to present music, stories, poetry readings, dramatic performances, and speeches. Students can record and listen to themselves with the help of tape recorders and similar devices. Music and foreign-language students, often record themselves as they practice, to hear how well they did. Lectures can also be recorded for later reviewing.
Sound information on magnetic tape can be stored in audio cassette and can be played on tape players. Information in digital (numerical) code is stored in audio compact discs, which last longer, offer better sound quality than cassette tapes and also allow the user to skip easily to any part of the recording. Audio CD’s can be played on CD players and on many computers.
Audio-visual materials, designed for both seeing and hearing have many benefits. They attract the attention and interest of the learner. They often provide the most direct way of conveying information. For example, schoolchildren learning about Mexico might use such audio-visual materials as a globe to find the country's location; recordings to hear Mexican folk songs; motion pictures and still pictures to study how the people live and work; and exhibits of things made or grown in Mexico.
With some audio-visual aids, such as chalkboards and projectors, the instructor can show a large group materials that could otherwise be shown to only a few persons at a time. Video presentations, computer systems, and telecommunications equipment are the primary multisensory aids.