Audio-visual materials, also known as instructional media, are educational devices that work through sight, sound, or both. Any combination of seeing and hearing information can greatly increase a person’s ability to remember what he or she learns. Teachers use a great variety of audio-visual materials in daily instruction. The materials range from simple devices like chalkboards to complicated digital multimedia systems.
The computer has become an increasingly influential educational tool. Originally, computers were used only to assist with regular learning programs, such as mathematics exercises. However, the sophistication of instructional computer programs has increased. Today, a multimedia computer can blend text, pictures, moving images, and sound to create instructional packages. PowerPoint is the trade name of one of the most popular multimedia applications. In addition, the Internet makes a vast amount of visual and audio information available to students in a matter of seconds.
Visual materials
are primarily for seeing. Such materials include pictures, maps, charts, models, or actual objects being discussed. They also include images projected onto screens or displayed on computers. But even with the increased capacity of computers to assist in education, the most popular visual aids continue to be devices upon which the instructor can write information. Chalkboards, dry-erase boards, and flip charts are the most commonly used of these devices.
Chalkboards, dry-erase boards, and flip charts.
Chalkboards are probably the most widely used visual aid. They are smooth, dark boards made of slate, glass, or wood. Users write or draw on the boards with chalk or crayon. Other accessories used with chalkboards include large protractors to measure angles and devices to draw the five lines of a musical staff. Teachers can also use patterns cut from cardboard to trace outlines on the chalkboard.
A dry-erase board is a steel surface coated with white enamel on which the user writes with special felt markers. Some dry-erase boards include a device that scans what is written on the board and makes paper copies to give to the audience.
Flip charts consist of large pads of paper mounted on a frame. The user writes information on the pad during a presentation or prepares it in advance to display while speaking. Material on a regular sheet of paper can be enlarged by a special machine for use on a flip chart. Compared to most chalkboards and dry-erase boards, flip charts are relatively small and portable. In addition, an instructor can display individual sheets of paper around the room so that the group can refer to important points presented earlier in the lesson. Business and industrial trainers frequently use flip charts.
Projection devices.
Many teachers supplement their lessons with material that can be projected onto a screen. Projectors display both solid and transparent objects. The most widely used projectors include opaque projectors, overhead projectors, filmstrip and slide projectors, and liquid crystal display projectors.
Opaque projectors show materials that cannot let light through them. These projectors can display on a screen an enlarged image of a book, document, or small object. Light from the projector lamp shines on the object. A tilted mirror reflects an image of the object and enlarges it through a lens onto a screen.
Overhead projectors project transparencies on a screen. A transparency is a clear plastic sheet with material printed on it. The transparency is placed on a clear flat surface over a projector lamp. A mirror reflects the image through a lens onto the screen. Transparencies can be made by several methods, including drawing or writing on a clear plastic sheet. They may also be made using photocopying machines, computer printers, and other devices.
Filmstrip projectors and slide projectors also project images onto a screen. A filmstrip is a strip of 35-millimeter film with a series of related still images that are displayed by a projector. Some filmstrip projectors have built-in tape players to provide sound to accompany the images. A 35-millimeter slide projector is used to show individual transparent photographs called slides. Slides are arranged in a tray from which they individually drop between a light and the lens that projects them. In many classrooms, computers and other devices have replaced filmstrip and slide projectors.
Liquid crystal display (LCD) projectors pick up information using a substance called liquid crystal, which changes color when an electric charge is applied to it. When attached to a computer, an LCD panel picks up and displays an image of what appears on the computer screen. With LCD projectors, teachers and others can present computer images, as well as play video clips and display computerized slide presentations. They can also present information from the World Wide Web. Many LCD projectors can project images from television systems.
Digital light processing (DLP) projectors create images using a special type of electronic circuit that contains up to 2 million tiny pivoting mirrors. Like LCD projectors, DLP projectors display computer images.
Audio materials
are primarily for hearing. They include audio cassette tapes, audio compact discs (CD’s), and the machines on which they are played. These materials are often used to present music, stories, poetry readings, dramatic performances, and speeches. With tape recorders and similar devices, students can record and listen to themselves. Music and foreign-language students, for example, often record themselves as they practice. They can then play the tape to hear how well they did. People also record lectures to review later.
Audio cassette tapes store sound information on magnetic tape and can be played on tape players. Audio compact discs store information in digital (numerical) code. Compact discs last longer and offer better sound quality than cassette tapes. They 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.
Multisensory materials
are designed for both seeing and hearing. As the availability of multimedia technology has grown, teachers have expanded the use of multisensory materials in instruction. Multisensory aids include video presentations, computer systems, and telecommunications equipment.
Video presentations.
Films, especially 16-millimeter films, were once a major multisensory instructional tool. In the late 1900’s, videotapes became more common. Videotape is easier to use, more durable than film, and less expensive. Videocassettes are a common form of videotape. Videocassette recorders (VCR’s) play back the tapes, which students usually view on television sets. The tapes can present motion pictures, television programming, or other presentations. But in many schools, multimedia computers perform many of the duties of VCR’s.
Like videocassettes, discs called DVD’s store materials that combine visuals and sound. The discs store information in digital code and are played using a computer or a DVD player connected to a television set. DVD’s offer high picture quality and the ability to skip easily to any part of the disc. Most DVD’s provide an on-screen table of contents that allows the user to select desired information.
Many schools have a video-production system, which includes equipment to produce and play back video presentations. More sophisticated systems may have various cameras, editing software and equipment, and audio equipment. They may also have computer graphics devices to create visual effects in producing videos. Computer graphics is a term that refers both to the use of computers to create pictures and to the pictures themselves. School video-production systems are used by teachers to produce educational material, as well as by students learning to work with television.
Other computerized tools.
As multimedia technology has improved, teachers have greatly expanded the use of computers in audio-visual instruction. The availability of content from the Internet has dramatically enhanced the ability of teachers to provide audio-visual materials to students. With high-speed access to the Internet, a teacher can present information—including text, photos, sounds, and videos—found on a website to a class. Students also can use computers and the Internet for research projects.
Computer tutorials are educational programs that lead students through study exercises and provide additional help if they give wrong answers. In addition, some publishers offer electronic books, also called e-books, that present textbook information through computers.
Computer simulations (representations that respond to changing conditions) enable students to experience realistic situations. For example, pilots in training use flight simulators, which imitate an airplane in flight. Computer simulations can also be used by an entire class. The scene for the simulation may be projected onto a screen for the class to see. The computer manages the input and output, while the class tries to work through the situation presented in the simulation. For example, a simulation program may present political problems facing a mayor and city council, with the class discussing possible solutions. An advantage of such programs is that a whole class can use one computer, which is less costly for schools than providing individual computers.
Computers and various telecommunications systems (systems that transmit information throughout the world) have allowed a development in educational media known as distance learning. Such technology enables students to work on the same project from two or more separate locations. Using computers, students may get connected through e-mail, electronic chat rooms, or direct Internet video connections. Teachers may use satellites or cable TV to transmit a lecture or other educational presentation to many locations. This enables many schools to share a class taught by one teacher. Distance education provides many students with instruction that would not be available to them otherwise. For example, a small college with limited resources could show on television a class taught by a well-known professor at a large university.
