There are some features, which can be used to determine the extent to which audio visual aids are of great value in a learning process. Their values depends upon the extent to which they assist in achieving the objectives of instructions and may be indicated briefly under the following heads:
Relevancy
The aid must be relevant to the concept which needs to be developed. A very important standard value is the extent to which any aid is directly related to the understanding of the subject matter. A visual aid could be accurate to the best details understandable and interesting and yet to be of little value because of its irrelevancy. For example, a teacher is trying to make clear the structure of sodium atom with the help of chart. If the teacher uses accurate and beautiful chart on which there are so many other atomic structure drawn. It will lose much of teaching value. Because of the presence of irrelevant material on the chart.
Accuracy
It is very important to make the audio visual aids accurate but it is difficult to make them as accurate as desired. The chart is always missing the third dimensional attribute and must be viewed from a fixed position. The models overcome both these difficulties but are seldom as accurate in the details as pictures. The accuracy of understanding is often considered to be important rather than the accuracy of specimen.
For example, if someone is teaching the principal parts of flowers by drawing an apple blossom. It is of littler importance whether the diagram resembles the apple blossom in every detail but the important thing will be to clarify the proper relation of such parts as sepals, petals, stamens etc. For this reason a good diagram might be of even greater value than an accurate photograph. So it is the accuracy of the concept produced rather than the accuracy of details (exactness) in visual aids, which is important. On the other hand a teacher uses a large model of a fern plant in his classroom and then finds that the students when given actual plant, do not recognize it as being the same thing.
Interest
Its presence makes the learning process very easy and its absence makes it a repulsive. Its presence makes the work a privilege and its absence makes it a punishment. It is a main job of the teacher to create interest in the students for learning. Almost all the subjects should be taught with the help of audio visual materials so many concepts in secondary classes that can be make interesting with the help for charts, models and films. For example atomic structure, molecules, and digestive system, historical events, mathematical figures, geographical maps and graphs etc.
Comprehensibility
In selecting and using visual aids we must try to choose those things as aids which relate the new experience with past experience and which are within the comprehension of the students who are to use it.
For example, a teacher finds that his class is experiencing considerable difficulty in locating and understanding the relation between the parts of a circulatory system. The teacher then draws purely a diagrammatic sketch on the black board clearly. This clarified the difficulties, because it is simple and readily comprehended by the students.
Motivation
How to motivate students for learning? Audio visual aids motivate learners as they make the learning process in classroom interesting especially in activity oriented subjects for effective learning.
Realism
A visual aid must possess the quality of developing real concepts of the things. Suppose we try to develop in our students the concept of the movement of electrons in the atom. We in this case try our best to describe accurately with the help of diagrams but the students are shown the actual film of the movements of electrons, a very different concept will be developed. Nearly all the visual aids are lacking one or the other characteristics but the actual specimen clarify the concept due to realism.
