Teaching Aids| Types of Teaching Aids in educational technology

 INTRODUCTION

As a discipline, educational technology extends beyond the total of its components.

In the present context, educational technology connotes a field of study including instructional design, audio-visual media, teaching–learning process, teaching strategies,

training strategies and assessment strategies. Educational technology is far more than just technology; its bases are psychology, social anthropology and sociology.

Early developments in this field defined the use of technology in education as the involvement of audio-visual equipment, i.e., hardware in educational processes. The use of hardware in teaching–learning results increased effectiveness of the education

process. This progression in the field changed the definition of technology in education,

i.e., methods and techniques of the teaching–learning process.

This signifies the software section of educational technology. The use of technology in education results in increased productivity through human capability.

Educational technology has to be understood as a science of techniques and methods,

by which educational goals can be realized, which makes it easy to adopt modern

technologies for improving the effectiveness of the educational process. Consequently,

machines and newer techniques are being employed in all areas of knowledge:

preservation, transmission and advancement. This extends educational technology

across wider boundaries. However, we need to understand that technology within

the confines of the classroom has many advantages as well as disadvantages. The

disadvantages include absence of adequate training, restricted access to technology

and extra time wasted in implementing new technologies. For better understanding

of educational technology, it is important to be familiar with the theories of human

behaviour, and how behaviour gets affected by technology. This necessitates the

adoption of a systematic procedure for using technology in the classroom at a narrow level and the whole educational process at a broad level. This gives way to different approaches to educational technology.

Educational technologies are not distinct technologies but intricate combinations

of hardware and software. These technologies may make use of some combination

of audio channels, computer code, data, graphics, video, or text. Technology

applications are generally recognized in terms of their most noticeable hardware

feature (e.g., a VCR or a computer). However, from the perspective of education,

the kind of learning imparted is more significant than the equipment delivering it. In this unit, you will learn about the various kinds of teaching aids used in the field of education.

4.1 UNIT OBJECTIVES

After going through this unit, you will be able to:

 Discuss the importance of teaching aids

 Assess the non-projected teaching aids used in classrooms

 Explain the various types of projected teaching aids applied in the field of education

 Analyse the role played by audio-visual aids in the field of education

 Understand the use of a computer as a teaching aid

4.2 TEACHING AIDS FOR TEACHING

‘The supply of teaching aids to every school is essential for the improvement of the quality of learning.’—Indian Education Commission (1964–66).

Education, whatever its specific goals or objectives, involves learning. Learning is a modification of behaviour which has been formed as the result of experiences or prior activities. The basic learning experiences, or the learning inputs, need to reach

the pupil through his senses. Senses are known as the gateways of knowledge.

Sense experiences provide a basis for intellectual activities. These experiences are gained through several auxiliary medium and materials, which are known as teaching aids. Teaching aids present verbal and abstract experiences in a concrete form, through which learning becomes permanent.

The cone of experience encourages direct and purposeful experiences which

makes learning meaningful. Intensive direct experiences enable permanent learning. It is clear from the above figure that verbal symbols are at the lowest level of

learning experiences, whereas direct purposeful experiences are considered to be the best. The other mediums are ordered in between these two extremes.

Thus, in order to derive optimum advantage from the application of teaching

aids, a teacher should know the place and importance of each of these aids in the teaching–learning process, as well as their utility and methods of evaluation.

Teaching aids can serve as a useful assistant to a teacher. However, these should not overtake or command him under any circumstances. In fact, a teacher should be focussing their operation during the teaching process.

Uses of Teaching Aids in Class

Merely collecting or assembling teaching aids is not a measure of success of the teaching process. It is also essential that these aids are used effectively. To achieve this, a teacher ought to know when and how to use them. If a teacher uses the teaching aids in the manner described below, then it is likely that the outcomes will be suitable, adequate and effective.

 Use in stages: Teaching aids should be used in three stages, i.e., during the introduction, the presentation and during revision. The objective of each of these three stages are different and teaching aids need to be used accordingly.

 Use as per need: Teaching aids should be used as and when necessary. If they are used when not needed, the students can get confused. This may also lead to indiscipline in the class.

 Giving time for thinking and observation: Teaching aids should not be used only for presentation or demonstration; the students should be given sufficient time for contemplation, observation and learning. Any queries from students should be adequately addressed.

 Variation in teaching aids: If the same type of teaching aids are used repeatedly, the students may get bored with them. Hence, there must be variety created by adopting different teaching aids from time to time.

 Removal of teaching aids after use: After demonstration and application of the teaching aids, they should be removed and stored appropriately. Also,

demonstrating more than one teaching aid at a time may cause confusion in the students’ minds.

Procedural Precautions in the Use of Teaching Aids

Teaching or audio-visual aids can be applied effectively if a teacher keeps the following in mind:

(i) In relation to teacher:

 The importance and objective of the teaching aids

 The students’ needs and interests

 The nature of the problem that needs to be communicated

 The selected teaching aids should be reviewed and edited continuously

(ii) In relation to classroom:

 The reason for selecting a particular teaching aid should be explained.

 The students must be clear as to what is expected of them.

 New terms and terminology being introduced must be clearly explained to the students.

(iii) In relation to presentation of material:

 The presentation should be effective

 Time management must be appropriate

 The response of students must be considered

(iv) In relation to summary:

 The teaching method should be reviewed and messages summarized from time to time.

 The suspicions and doubts of the students should be clarified and eradicated.

 If necessary, students should be tested from time to time.

(v) In relation to feedback:

 The students should be given assignments.

 The students should be given an opportunity to apply the newly acquired knowledge.

A teacher should pay special attention to the following aspects in order to ensure that the teaching aids are used effectively:

 A clear relationship between the aids and the instructional objectives

 Selection of suitable teaching aids

 Suitable opportunity for application of the aids

 Adequate duration for application and experimentation

 Proper arrangements for demonstration of the aids

 Aids should be related to the subject matter and should not be a mere pastime or of recreational value

 They should match the behaviour of the students

 They should be of good quality and realistic

 They should be motivational

 They should be easily available

 They should be useful

A teacher should be careful when applying and preserving teaching aids. He should

store them properly, and also take care to rectify defects, if any, himself. It is advisable

for him to rehearse an experiment before demonstrating it using a teaching aid in the

classroom. He should also be fully trained in the use of teaching aids.

Importance of Teaching Aids in Classroom Teaching

The importance of teaching aids in classroom teaching are is that they:

 Attract the attention of the students quite effectively

 Have a high motivational impact

 Achieve permanent learning within a limited time frame

 Encourage meaningful use of words and reduce verbosity

 Provide a first-hand experience

 Introduce an element of reality into the classroom

 Simplify the work of the teacher

 Reduce the monotony in the classroom

 Reduce the impact of a language barrier in the classroom

 Help to establish continuity in the thought flow

 Improve understanding

 Encourage self-activity

Principles for Selection of Teaching Aids

The selection of suitable teaching aids is critical for the success of the learning process. An unsuitable selection may result in more harm than good, because this

can create confusion in the minds of the students. A teacher should keep in mind the following while selecting teaching aids:

 Principle of selection: The selected teaching aids must have certain basic traits. They should be important from an educational viewpoint. They must be interesting and able to motivate the students towards the learning goals.

They should be result oriented, i.e., focused on the achievement of the instructional objectives.

 Principle of preparation: A teacher should devote himself in making the students psychologically ready for the teaching aids. He must be familiar with the nature of the selected teaching aids. Before he demonstrates the

aids in the class, he himself must thoroughly inspect the teaching aids in all respects.

 Principle of proper presentation: The teacher should ensure that the subject matter and the teaching aids are coordinated and related. Teaching aids should

be used as supplementary tools, and the teacher should be fully proficient in their use.

 Principle of control: The teaching aids should be under the control of the teacher during the entire period. There must be no situation wherein the teacher is unable to control or use the teaching aid properly.

4.2.1 Psychology of using Teaching Aids/Audio-visual Aids

In addition to reading, vicarious experience can be gained from still pictures, films,

filmstrips, resource persons, simulations, mock-ups, television and the like. The more

concrete and realistic the vicarious experience, the more closely it approaches the learning effectiveness of the first level. Of course, unless the learner realizes that he is dealing with a substitute, his learning may not be comparable to that of real-life learning.

Interest in the role of the senses in learning was already there in educational

circles when instructional media began their ascendancy. It has long been recognized that the various senses condition the reception of messages in the communication act. Research done by Cobun (1968) indicated that:

 1 per cent of what is learned is from the sense of taste

 1.5 per cent of what is learned is from the sense of touch

 3.5 per cent of what is learned is from the sense of smell

 11 per cent of what is learned is from the sense of hearing

 83 per cent of what is learned is from the sense of sight

 Retention of what is learned is likewise related to the sense experience.

TYPES OF TEACHING AIDS

The type of equipment used in classrooms have a huge impact on the teaching-learing process. There are different types of teaching aids used in schools today,

such as audio-visual, chalkboards, wallcharts, models and so on. We discuss them in detail in the following section.

4.3.1 Non-projected Aids

As the name proposes, non-projected displays comprise every type of visual display that can be shown to a group of students without the use of any optical or electronic

projector. They use the most fundamental types of visual aids that teachers and trainers can avail. A few of the popular non-projected displays are discussed in this section.

(i) Chalkboards

These boards are dark in colour, so that chalk can be used to write on them

(Figure 4.2). They are the most popularly used visual aids despite the fact that

overhead projectors present the same information in a better manner. This is because

chalkboards are easy to handle and produce or customize during the course of a

lesson; and also to explain calculations and similar exercises to a class of students.

It is probably the cheapest and most widely used form of hardware in formal teaching–

learning situations. A good chalkboard is 4 × 6 or 4 × 7 or 4 × 8 feet in size, and is

made up of slate or glass. It is fixed on the wall at a height of at least 3 feet and is

grey, black or green in colour. Now, we also have white boards on which we use

multi-coloured pens for writing. These can be wiped off with a damp cloth. These

boards are made of wood and their surface is very smooth. A chalkboard provides:

(i) a visual presentation of the main teaching points, (ii) a structured record of the content of the session, (iii) a basis for summarizing, (iv) a guide for trainees to take notes from, and (v) additional effect to spoken words or lecture.

The advantages of using chalkboard are:

 They are easily available

 They can be used without much advance preparation

 Notes and diagrams can be built up as the lesson progresses

 Points can be added and deleted

 The ideas and words of trainees can be easily included in the summary

 Learners can be involved in writing answers, comments

The unique features and advantages associated with a chalkboard make it

the most important and essential aid to teaching and learning in all the subjects of the

school curriculum. It is the only aid that is easily accessible to both teachers and

students for visualizing the subject matter and diversified subject areas of the school

curriculum. When used by a teacher, several points should be borne in mind, such as

proper selection of the portion of the chalkboard, regular and proper cleaning of the chalkboard, use of good quality chalks; suitable lettering size for visibility, appropriate

angle of writing, and non-traditional use for delivering maximum benefit to students etc.

(ii) Marker Boards

Training halls and teaching rooms often have these boards, which are gradually replacing the conventional chalkboards. These are popularly also known as

‘whiteboards’. They are big, white or light-coloured plastic sheets, with surfaces

that can be written on. Writing instruments like felt pens, markers or crayons can be used to write on these sheets. Nevertheless, marker boards have the following

advantages, when compared with chalkboards:

 There is a lot of mess associated with the usage of chalkboards, even when ‘dustless’ chalk is used. Marker boards do away with this mess.

 One can use many colours and shades for better, sharper and well-defined display of drawings and written text.

 Unlike a chalkboard, a marker board can work like a projection screen, if required One disadvantage of using marker boards on a long-term basis is the difficulty

faced when cleaning its surface. After a period of time, writing impressions left

behind cannot be erased. Hence, the use of special marker pens is advised, which are recommended by the maker of the board. The board should be cleaned regularly with a damp cloth dipped in the specific cleaning fluid or solvent.

(iii) Electronic marker boards

As technology has developed, electronic marker boards have gained wide acceptance.

Electronic marker boards have an edge over manual ones as they can facilitate

photo-electronic scan of the written text or drawings on its surface. Some of these

boards also have the feature of producing miniature hard copies of the material.

Multiple hardcopies can be produced for distribution among members of a class or

group. The use of electronic marker boards is limited owing to their high cost.

Some electronic marker boards can scan the material written or drawn on

them, so this material can be practically produced and loaded on a communication

network and linked with other locations. An appropriate display system can also enable one to view the material from different locations. These types of electronic

marker boards offer a suitable platform for interactive communication with distance-learning students. This is the reason that they are so widely used by many educational institutes and universities that offer distance-learning courses.

Their utility is much higher for students in remote areas. They are popularly known as ‘smart boards’ in Indian settings.

(iv) Adhesive Displays

Adhesive displays also fall in the category of non-projected display media. In these,

the material to be displayed is stuck on the surface without the use of drawing pins or glue. Adhesive displays comprise felt boards, hook and loop boards and magnetic boards.

(a) Felt boards

Felt boards are also called flannel-boards or flannel-graphs. These types of boards

use shapes cut out of felt, flannel or similar material that can stick to the display

surface. They make use of rationally reasonable, easily portable, and very useful

technique of display. Felt board are useful for creating both permanent and temporary

displays that can be mounted on walls. Nevertheless, they find most appropriate use in exhibited displays like table settings, corporate structures, jigsaw puzzles, and in fundamental mathematical and geometrical concepts.

(b) Hook and loop boards

Hook and loop boards work on the same principle as felt boards. They are also known as teazle boards or teazle-graphs (Figure 4.6). However, these boards use

special material (like velcro), with many tiny hooks attached to it. On the other hand,

the display surface has a covering of small loops which can be attached to the hooks. These hooks and loops allow the tagging of heavier display material, as and

when required. Hook and loop boards are used on the same lines as felt boards, but the added advantage is the provision to heavy display material.

(c) Magnetic boards

The magnetic board is also a type of adhesive board. These boards have higher utility and versatility, in comparison to felt boards and hook and loop boards. Different types of magnetic boards are available in the market. The latest version comprises

sheets of ferromagnetic material, which are coated with special paint on which one

can write or draw using suitable markers or pens. All types of board enable display

items made of (or backed with) magnetic material to be stuck to and moved about on their surfaces.

These boards also enable movable display to be supplemented by writing or drawing on them. Thus, with the help of magnetic boards (Figure 4.7), highly

complicated and refined displays can be created. These displays enable users to clearly exhibit movement and change in systems. They operate as an excellent

medium to demonstrate a teaching strategy or to conduct sports related training. To create an exhibit for a basketball or a football team, a permanent field can be painted

on the board. Magnetic discs can be used to identify every player. Each magnetic disc can be rearranged and moved around, as and when required. Appropriate arrows

and lines made by chalk or marker pens can be used to express different movements, and run patterns.

(v) Charts, Posters and Flat Displays

Different forms of charts, posters and other flat pictorial displays have a high usage

and versatility among teachers and instructors. We learn about some of the important varieties in this section.

(a) Flip charts

Flip charts are one of the simplest flat type displays. Information can be effectively

displayed to a class or a small group of learners through flip charts. These comprise

several large sheets of paper, which are attached to a support bar, easel or a display

board with the help of clamps or pins. This makes it possible to flip the charts

backward or forward, as per the requirements of the teaching–learning situation.

There are two basic uses of such charts. A sequential progression of already designed

sheets can be displayed through flip charts. This can be done in the desired sequence by flipping one sheet over the other. The following precautions should be kept in

mind while preparing flip chart sequences:

 The message on every sheet should be easy to understand.

 All that is written or drawn on every sheet should be visible to every member of the core group.

 The print quality and size should be inspected by the teacher/trainer by viewing it from every part of the room.

Flip charts are also useful to jot down content spontaneously during the course

of a session or training. They can also be used to make a listing of responses,

questions and ideas from learners or concerned groups.

(b) Wallcharts

Different forms of wallcharts are used in every sector of education and training.

They are widely used because they are versatile and simple. They have entered the teaching–learning scenario in the sophisticated form of visual aids. Charts and wallcharts cannot be differentiated clearly. In simple terminology, any chart that can be put up on a wall or a noticeboard can be called a wallchart. The main purpose of wallcharts is the area of casual study outside the context of a formal session. The information on charts has a higher level of clarity, when compared to that on wallcharts. In addition to this, they differ in their usage and construction. The common

factors in both wallcharts and simple charts is that their sizes can vary and they can comprise more information when compared to overhead transparencies or a 35-mm slide.

Charts offer the following advantages:

 Clean presentation

 Portability from one place to another

 Availability of material for summing up

The drawbacks of charts are as follows:

 Limited space on each sheet

 Need to be stored carefully to avoid folds

 Cannot add or remove matter from the sheets

 Are not very durable

Charts can be used to explain important concepts and for recapitulation. Charts

that can be referred to learners for content, as and when required, are called

‘reference charts’.

(c) Metaplan charts

The metaplan system consists of lightweight pinboards like those made of thermocol,

brown sheets, thick cards in different shapes and colours. Other materials used in these charts are felt-tipped markers and glue.

In this system, the participants are asked questions relevant to the theme of the session and to write their views on cards. These cards are collected and shuffled

to ensure anonymity. Then they are read out and pinned on boards. It helps to get a collective view of ideas from those involved. Pinboards can be as large as black-

boards. The number of pinboards required will depend on the number of trainees,

and themes. Normally, two to three boards are required for each session or theme.

If there are 24 participants who are divided into three groups and three sessions to use the metaplan system, nine boards will be required. Both sides of the board can

be used, which gives flexibility and space.

(d) Posters

S. K. Mangal, in his book, Teaching of Social Studies, defined poster as ‘a graphical

representation of some strong emotional appeal or propaganda carried out through a combination of graphic material like pictures, cartoons, lettering, and other visual art on a placard, primarily intended to catch and hold the attention of the viewers and then forcefully conveying and implanting in their mind a specific fact, idea or message.

Since a poster is designed to make a public announcement of a special idea, it

usually includes an illustration with a brief caption. It supports local demonstrations,

exhibits or activities. The purpose served by a poster can be as follows:

 Catch attention

 Create an impression of a fact or an idea

 Stimulate to support an idea

 Motivate to seek more information and to move towards action

They can be specifically used at different stages of delivering a lesson. Similarly,

they can also be used in presentations, practice and recapitulation stages to focus attention of the learner on some specific idea, event or process. A good poster

usually concentrates on a single idea and shows a unity of purpose. It is quite helpful

in effectively impressing inherent facts, ideas or messages on the minds of children.

(vi)Three-Dimensional Display Materials

Display materials discussed till now were all two-dimensional displays. This section

discusses a group of non-projected displays, which are three-dimensional. Non-projected displays are divided into three categories: (i) mobiles, (ii) models, and (iii) dioramas.

(a) Mobiles

Basically, a mobile is a three a three-dimensional wallchart. However, individual

components of this wallchart can be moved around. This is a system where pictures,

words,can be drawn on card or stencilled on some metal. Fine threads can be used

to hang them separately after cutting them, instead of hanging them on a wall. The resulting display is capable of changing shape and direction, in response to air currents.

These displays can be hung from any corner of a room where they are visible to anyone who enters the room.

(b) Models

Models can be identified as three-dimensional representations of real or abstract

items. A broad range of instructional and teaching–learning situations make extensive

use of models. They are primarily used as:

 Visual support material for large-scale education

 Objects for study or manipulation in individual learning

 Construction projects for individuals, small groups or entire classes.

Models are more specifically used to:

 Modify objects so that they can be easily observed and handled; this includes

both reducing very large objects and enlarging very small objects

 Clearly demonstrate interior structures of objects or systems as two-

dimensional representations are not capable to give this degree of clarity.

Products of virtual-reality that provide this clarity are very expensive  Exhibit movement, which is not possible in case of two-dimensional displays

 Display complex parts of a process in a simple way for learners to understand;

by focusing only on significant areas and eliminating all that is complex and causes confusion

Instructors or teachers should keep in mind that if viewed from a distance,

even three-dimensional displays appear like two-dimensional ones. Hence, the

distance of the learners from a model should be optimum for them to view it clearly.

(c) Dioramas

Dioramas are still-display systems which can combine three-dimensional foreground

images with two-dimensional background. The effect thus created is realistic. They can be used to teach a number of subjects, including:

 Biology and natural history (showing plants or animals in their natural environment)

 Architecture, geography and geology (showing buildings, cities, surroundings, primitive landscapes, sites, etc.)

 History, theatre, spiritual learning (illustrations of scenes from history or drama, stage sets, battles, etc.)

.3.2 Projected Aids

Visual displays that are without movement are known as still projected displays.

These displays rely on optical projectors. The visual aids involved in still projected displays are discussed in this section.

(i) Overhead Projector

An overhead projector (OHP) is a machine which projects light from a lamp through a transparent surface, onto a wall or a screen. The transparent surface (transparency)

is the small sheet of plastic that has text or drawing on it. This writing or a drawing

appears much enlarged and in exact form and shape, on a blank surface (wall). It helps a teacher to explain a point to the learner with the help of a visual.

Principle: Light is furnished by a 500 to 1,000 watts lamp, and is reflected

upward to a projection stage or screen and into an objective lens, which is centrally

supported above the stage. The light strikes a mirror and is reflected onto the screen

behind the operator. The lens and mirror stand above the machine. The machine

may rest on a desk or it may be on a projection stand, or table. Thus, the teacher

may sit or stand in front of the class. The screen can be a flat, smooth, white/pale

wall. A good and inexpensive screen can also be made from a hardboard. The rough

side of the hardboard should be covered with two coats of white emulsion paint.

This board may be hung in one corner of the room. The screen should not be reflective.

An overhead projector provides educators with an easy, low-cost interactive

environment. Plastic sheets are used as teaching material, which facilitate the educator

to write on them with the help of non-permanent and washable coloured board pens.

These transparencies can be pre-printed and used in repetition. Thus, they save a lot of time for the teacher or any other user.

The overhead placement should be such that it is convenient for the instructor

to use. Further, the educator should be able to face the class, to facilitate better

interaction with the students. Since the projector is able to enlarge small script, the educator can write in his own desired font size. He does not need to continuously

stretch his arm to write on the board. Unlike a blackboard, time is not wasted in

erasing what has been written. Once transparencies are used, they can be restored

to their original unused state after washing them with soap and water.

Advantages of overhead projector

An overhead projector has the following advantages:

 When using OHP, a teacher can always face the class and thus maintain eye contact with the students.

 Pre-prepared matter can also be displayed with the help of OHP.

 OHP transparencies can be used repeatedly, which gives the teacher more time to engage in discussions with learners.

 The subject displayed on OHPs also helps learners to retain the lesson learnt.

 Many techniques (free-hand writing or drawing, typing, photocopying, desktop publishing and so on) can be used to prepare OHP transparencies.

In comparison to other types of visual aids (e.g., charts), overhead

transparencies are relatively compact and can thus be easily stored in suitable

boxes, large envelopes, folders or files.

 All the lights of a room need not be switched off when using an OHP. This

enables students to take notes.

 Small objects may be shown on the machine simply by placing them on the

projection stage. They will be projected as silhouettes.

 No extra projectionist or person is required to project.

 The clarity of display in a OHP is higher than that on a blackboard.

 The instructor may prepare an entire course which is time saving.

 The operation of OHP does not require any technical skill and knowledge making it user-friendly. Moreover, it is also clean and quiet.

Disadvantages of overhead projector

The disadvantages of overhead projector are as follows:

 OHPs run on electricity and require white surfaces for projection.

 When compared to chalkboards, their maintenance is somewhat time-consuming.

 They have a tendency to break down at times.

 Light from the projector can be irritating.

 Sometimes, positioning of the screen becomes difficult.

 Any error in spelling or pictures are magnified and distract the participants.

 Efficient usage of OHP requires sufficient time, effort and display material in the form of transparencies.

Basic instructions for using OHP

The following basic rules need to be followed for making optimum use of OHP:

 The appropriate positioning of the projector and the screen is of utmost

importance. They should be placed in such a manner every participant is able

to see the screen easily. Generally, the screen should be placed in one of the

front corners of the room, because that leaves the teacher with access to the fixed chalkboard or marker board, which he/she might need at anytime during the session.

 The placement of the projector and screen should reduce or do away with

two forms of keystoning. One form of keystoning emerges when the axis of projection is not horizontally perpendicular to the screen. This can be reduced

when the projector is kept opposite to the centre of the screen. Another form of keystoning emerges when the axis of projection is not vertically perpendicular to the screen. Often, this can be lessened to a reasonable extent 

if the screen is tilted forward a bit. If the screen is fixed vertically, the problem can only be resolved by raising the level of the overhead projector. However, this should not block the learners’ view of the screen.

The distance of the projector from the screen should be adjusted in such a

manner that the entire screen covers the image proportionally, when in proper

focus. If the focus is not proper, the people sitting far away from the projector

will not be able to see the details on the screen clearly.

 The surface of the lens should be clean and dust-free. Dusty surface of lens

make the images opaque. It is recommended to use methylated or surgical

spirit and soft cloth to clean the lens.

(ii) Slide Projector

Slide projector or diascope is popularly known as ‘magic lantern’. It is an optical aid

to the process of teaching. It is used for projecting pictures from a transparent slide

onto a wall or a screen. Since it is used to project slides, it is called a slide projector.

A slide projector is useful for small as well as large groups. It comprises four sections:

(i) electric incandescent light bulb or similar source of light (usually fan-cooled), (ii)

reflector and ‘condensing’ lens to focus the light onto the slide,

(iii) a holder for the slide, and (iv) a focusing lens. It helps to project a larger image

of the slide. When the figure or illustration is very small and it is required that the

whole class should see it clearly, a transparent slide of this small figure is prepared.

The slide is placed inverted on the slide carrier of the magic lantern (slide projector).

The slide projector projects its erect image on the wall or screen by enlarging its

dimensions and making the vision sharper and clearer. A coloured slide or filmstrip is more attractive.

Filmstrip projector works on the principle of direct projection. Light rays emerge directly from the projection lamp or other source of illumination, pass through

condenser lenses, the filmstrip/slide and the objective lens to produce an enlarged

image on the screen. The source of light can be an electric bulb or a kerosene or petromax lantern. Images are directly projected as they are, when a filmstrip/slide is

used. This allows them to be projected even if the room is semi-darkened, at a desired speed. 

Advantages of slide projector

The advantages of slide projector are as follows:

 Educational information: The slide projector has immense educational value because of the variety of information it can transmit like maps, drawings,

diagrams, and photographs. It enables a subject to be taught clearly and in detail. To make it more effective, a tape recorder can also be used along with

the slide projector. The teacher can record a narration on a tape recorder and synchronize it with the slide projector such that it gives the necessary

commentary pertaining to the slide without the teacher’s intervention.

 Motivational force: It arouses the attention and interest of students.

A projected image is more effective in capturing the attention of the audience

for a longer duration. It is the best way to motivate students towards better learning.

 Easy to transport: Slide projectors are light and easy to transport.

 Easy to use: Slide projector is easy to use. It is a simple device that can be

operated and focused using a remote control.

 Consistency of images: Images can remain on the screen as long as the students want them to.

 Interesting: The whole activity arouses interest in students.

 Economical: There is no wastage of time and energy.

 Inexpensive: Slide projectors are not costly. Any school can afford it.

 Non-fragile: It is not easily broken.

 Non-inflammable: It is non inflammable.

Disadvantages of slide projector

The disadvantages of slide projector are as follows:

 Not always suitable: Every type of material cannot be projected by the slide projector.

 Not excessive use: Since glass slides are becoming expensive now, the slide projectors may not be used excessively.

(iii) Filmstrips

Filmstrips may be used in slide projectors as well as filmstrip projectors. Instead of

using different slide for different topics or more slides for one topic, one strip or

piece of still film is prepared. Slides produced on films are called filmstrips. A filmstrip

is made of cellulose acetate and is 16 mm or 35 mm wide and 2 to 5 feet long. It usually consists of 40 to 100 separate pictures related to a particular subject, topic or

theme. These pictures may be connected with series of drawings, photographs,

diagrams, or combination of these. Such a strip or a piece of still film serves the same purpose as served by a number of slides.

In a slide projector we use separate slides, while in a filmstrip a strip of film

(having many slides) is exhibited. The filmstrip projector is a recent development

and it is becoming a more popular means of pictorial representation. Various

commercial firms sell such readymade filmstrips for different topics of different

subjects for different age groups. Filmstrips are also available on loan, free of charge

from the Central Film Library, Central Institute of Educational Technology and NCERT.

Advantages of filmstrip

The advantages of filmstrip are as follows:

 It is easy to operate

 A frame may be held on the screen as long as it is required

 Strips of educative value, according to special needs, are available

 It is possible to review previously exhibited frames again for reference

 It can be used to transmit varieties of information

 Now filmstrips are available with commentary recorded on tapes

 The teacher can also record his comments and play the tape, synchronizing it

with the frame of the filmstrip

 Filmstrips are light in weight and easy to carry

 Even a low voltage lamp can serve the purpose while using filmstrips

 With every filmstrip projector, a 2 × 2 slide attachment is also provided and

the same projector can also be used for projecting slides

 Its use does not restrict the normal flow of conversation between the teacher and the class

 Numbered filmstrips are advantageous for the learner, especially when one

or two students use them in independent work. Numbering makes it possible to locate the frames

 Since filmstrips present pictures in a fixed sequence, they provide a structure for the subject

 Filmstrips provide economic means of presenting information 

Disadvantage of filmstrip

Filmstrips lack audition: The teacher has to work like a commentator along with the filmstrip being projected.

(iv) Epidiascope

An epidiascope projects small opaque images of maps, photographs, and pages of a book on a screen, in an enlarged manner. It is a combination of an episcope and diascope. The epidiascope works by reflecting light from an opaque surface (opaque

projection). A lamp illuminates the material. The image is reflected by a mirror, through a lens onto the screen.

It is used for making classroom teaching more interesting and effective. This

device does not require slides. Teaching aids like maps, charts, small pictures, graphs,

line drawing are directly projected on the screen. The size of small pictures can be

magnified or enlarged by the epidiascope. In epidiascope slides, transparencies are

also used. It also facilitates books and original matter or teaching aids to be directly

projected on the screen. Therefore, the epidiascope is commonly used in classroom

presentations. It also makes lessons interesting and effective.

Advantages of epidiascope

The epidiascope has general and specific advantages:

General in

 Easy to handle

 Projects a wide variety of materials in a magnified form

 The colour of object is also transmitted onto the screen

 Teachers can have time for class discussions

 Often, an excellent outlet for creative work

 It has a robust mechanism Specific

 Photographs and pictures can be projected (these are difficult to draw)

 Teaching material can be directly projected from books or other original sources

 Small objects can be projected after demonstration 

Disadvantages of epidiascope

Some of the limitations associated with epidiascope are as follows:

 Pages must be flat when books are being used

 Materials sensitive to heat is to be avoided

 Projection by reflected light is less efficient and requires total darkness

 Machine is too bulky to be easily carried

 The operator cannot face the audience

 Projector must be kept near the screen

 Expensive in terms of cost

Precautions to be kept in mind while using epidiascope

 Before teaching, the epidiascope and the screen should be set in the classroom properly.

 It requires a dark room for projecting teaching aids so that proper arrangements should be made for the purpose.

 The size of teaching aids should be according to the size of the epidiascope’s aperture.

 The teacher should give his comments simultaneously while projecting the teaching material.

 The teacher should make use of a pointer for indicating the aspects of a diagram or picture.

(v) Microfilm and Microfiche

Microfilms are 35-mm films, which contain photographed reading material. Each

frame contains materials of one page. The rolls of microfilm are placed in microfilm

readers which project each page on a revision screen. Microfiche is a miniature

form of microfilm. This is a sheet of film carrying many rows of images of printed

matter. Microfiche is reduced in size, in comparison to microfilm. Both microfilm

and microfiche can be stored, retrieved, and projected for reading. They have great educational potential. 

Audio-visual Aids

Electronic resources have also made their foray into the field of education, in the last century. In 1920 it was the radio, and in 1950 the television began to be used

widely as educational tools. The usage of radio and television in broadcasting for education has assumed three general approaches:

 Direct class teaching: Where temporarily, teachers are replaced by broadcast programming substitutes

 School broadcasting: Where complementary teaching and learning resources are offered by broadcast programming

 General educational programming: Which offers general and informal educational opportunities

This section would discuss both of these electronic resources in brief.

(i) Radio

Radio basically transmits signals through free space enabled by modulation of

electromagnetic waves having frequencies lower than visible light. This is done by

oscillating electromagnetic fields that pass through air and the vacuum of space,

which makes electromagnetic radiation travel. By systematically changing

(modulating) some property of radiated waves, such as amplitude, frequency, phase,

or pulse-width, information is carried from one place to another. The oscillating

fields induce an alternating current in the conductor, when radio waves pass an

electrical conductor. This can be detected and transformed into sound or other signals that carry information.

According to Butcher (2003), ‘radio has been used in education ever since its

availability’. Pennycuick (1993) of the Centre for International Education at the

University of Sussex, states more specifically that interactive radio instruction (IRI)

is characterized by ‘highly coordinated’ instructional materials and delivery strategies.

It includes elements of active participation on the part of the students. In spite of technological advancements, radio remains the key media to which most rural people

have access. Educational radio initiatives in different developing countries were

effective in providing topical programmes and reaching large numbers of learners

rapidly. Further, radio broadcasting is one of the greatest educational tools, which

has ever been placed at the disposal of civilized man. It is an instantaneous and universal means of communication. Broadcasting is relatively new, as far as its age is concerned. However, in a short period, it has been determined definitely that it

can perform three separate major functions— (i) it can sell goods and services; (ii)

it can provide entertainment; and (iii) it can make education, culture and information

available. Radio can be educative in formal as well as informal situations. The

medium of radio is very effective for broadcast of lectures by eminent educationists,

scientists, and historical statements. It is a rich medium for broadcast of drama,

stories, commentary, sports news, educational news and educational programmes.

It is popular in both urban and rural settings. Radio programmes are generally prepared

on topics which are more suitable to verbal communication. In India, AIR and other

radio channels render valuable assistance to classroom instructional programmes.

The limitations of radio broadcasting are:

 It uses only the sense of hearing

 It is a one-way communication

(ii) Television

Education television excels as a medium of large-scale delivery of information. In

modern times, television is an integral part of our culture. TV provides entertainment,

news, education, culture, weather, and sports. Television is the most powerful medium

of mass communication that has ever existed and it has revolutionized our life in

many ways. It appears that the future television is going to have definite positive

contribution to make children’s life in the classroom happy (M. J. Apter). Television

is already widely being used in schools. It is a powerful medium of communication

that calls for the use of auditory as well as visual sense of learners in receiving education.

Television offers many benefits to children and learners in general, including:

 TV enables the sharing of cultural experiences and thus brings the world closer.

 In Indian setting, specifically where bonding is valued, viewing of programmes gives the family members of all ages, an opportunity to spend time together.

 Television can be used by parents as a catalyst to get children into the

habit of reading. This can be done by following up televised programmes through books on same subjects.

 Exhibiting social responsibility, television can spread cultural and family values in an implicit manner.

 Television programmes provide an opportunity to parents to explore and

discuss controversial or sensitive issues with children.

 Learning skills and even socialization of young children can be developed

through balanced and efficient use of educational programmes.

 Young people can become more aware of other cultures and people through

news, current events and historical programming.

 Documentaries can give rise to judgmental thoughts concerning society and the world.

 The world of art and music can be opened for people by cultural programming on television.

 Televised instructions have the potential of improving the process and

products of learning as they involve thorough planning, systematic

presentation and integration of a wide range of audio-visual material and appliances.

Television is an important aid to teachers, supervisors and educational planners.

It has been utilized for informal and formal education and for distance and

correspondence education. There are some limitations associated with television in

the form of one-way communication, impersonal nature, passive learning, no interaction, and expensive media.

India, like other developing countries, has been using television for enriching

and improving the quality of education at every level. It has been particularly used

for expanding educational facilities, particularly in rural and backward areas, for

normal and informal systems. New dimensions have been added to the use of television

for instructional purposes with the advent of satellites. So far there has been use of

open circuit television in India. Closed circuit use of television for educational purposes

has not been explored much. Closed circuit television broadcasting is a sort of micro-

level local arrangement limited to a single school, or several schools located in a

particular region. The schools are connected by a cable or microwave system. The

telecast cannot be received outside the selected network and signal is not required to meet the commercial broadcasting regulations.

(iii) Closed Circuit Television (CCTV)

Televisions systems have assumed an important place in our daily life as it is one of

the most indispensable means of information and communications. Television

broadcasts are a form of ‘open-circuit system’, which are accessed by indefinite

number of people. Another form of circuit systems are ‘closed-circuit systems’,

which are designed to provide video to specified viewers. CCTV system is a system

that has been primarily designed for surveillance purposes. CCTV is very useful in

areas associated with security, disaster prevention, energy and manpower saving,

sales promotion and information services, production management, industrial

measurement, medical care, education and military fields. Specifically in the field of

instruction and education, CCTV has a wide applicability. It enables schools or institutions to develop and allow their students to access specific programmes thatare needed for their overall growth and development.

The definite advantages offered by CCTV have been highlighted as follows:

 Many CCTV systems are suited for distant viewing. The images

broadcasted by them probably comprise photographs from space, snapshots

of furnaces or other industrial equipment, and biological hazards.

 The use of CCTV would ease the shortage of good instructors or teachers,

reduce instructional costs, provide uniform instructions to a large number

of students simultaneously, and facilitate repetitive representation of resource persons or material.

 The use of CCTV provides a platform for desired exchange of man-

material resources, learning and instructional activities, courses and events

not only among students and staff of the same institution, but also among various institutions on the network of CCTV.

(iv) Video Cassette Reorder

The Video cassette recorder (VCR) is an electronic device that plays VHS or

beta tapes containing recorded movies and other programmes (like music videos,

exercise videos, etc.). A VCR has to be connected to a TV for viewing a recorded

programme. A number of variants of VCR have been produced over the years, in

addition to the traditional home VCR. These include combined ‘all-in-one’ devices

such as the televideo (a TV and VCR in one unit) and DVD/VCR units and even

TV/VCR/DVD all-in-one units. A camcorder merges a video camera and VCR in one machine.

VCR can not only play pre-recorded cassettes, but also record any programme

and replay it. Thus, educational television programmes can be recorded and later on

shown to students. With the help of video cassette recorders, educational and other

useful events can be recorded for teaching purposes. The replay of those programmes

in colour makes viewing very interesting and leaves a considerable impact on viewers.

Advantages of VCR:

The advantages of VCR are as follows:

 The operation of a video cassette recorder is very simple.

 It is portable and can be moved from one place to the other easily.

 Knowledge acquired by video is permanent.

 It is helpful to students in providing them knowledge of social and political

conditions of different countries.

 It is helpful in developing the thoughts and reasoning power of students.

 It is equally useful for children of varying abilities.

 The teacher can remove the doubts of students simultaneously, which is not

possible in a television lesson.

 The teacher can control the video presentation.

 Pictures on a VCR can be repeated as many times as required.

 Video films on different teaching subjects are easily available.

(v) Motion Picture

A motion picture (sometimes called a movie or film) is a series of still pictures

(frames) usually 8 mm or 16 mm in size, taken in rapid succession. When projected

by a motion picture projector, they give an illusion of motion (Gerlach and Ely,1980)

Films vary in length from one minute or less, to 50 minutes or more. If a 6-mm motion picture runs for more than 50 minutes in length, it is usually stored on two or more reels. The speed at which a film is projected varies with the format of the film. A sound 16-mm film is projected at 24 frames per second (fps) and super 8-

mm films, at 18 fps. Therefore, it is possible to show films in such a manner as to

create three types of images:

 Normal motion

 Fast motion

 Slow motion

Motion pictures are very useful in teaching various subjects like literature, drama,

history, geography and science subjects. Motion pictures motivate students as they

enjoy the medium. They bring people, country, events, on the screen. However, they

are expensive and subject to damage, if used extensively.

Hoban and Ormer have revealed the following educational advantages of motion pictures:

 Good films can be used as sole means of imparting certain factual

information and developing performance skills.

 Pupils will change or develop attitude and opinions, as a result of viewing films.

 Pupils will learn more from films if they are properly prepared and motivated.

 Learning will increase with repeated screenings of a film. Short single-concept films have certain advantages.

 Pupils can develop the will of problem-solving by viewing well-produced films.

 The ability to learn from films will increase with practice.

Amidst these advantages, it should not be assumed that learning would occur

only by watching films. The method of presentation may be inadequate or the film

may not be suitable for students of a particular age. Therefore, sufficient care should

be taken while selecting a film. It should be borne in mind that films with built-in

viewer participation and repetition of key points increase learning. If these factors

are lacking in a film, then these should be supplied by the teacher during or immediately after screening of the film.

(vi) Tape Recorder

An audio tape recorder, tape deck, reel-to-reel tape deck, cassette deck or tape

machine is an audio storage device that records and plays back sounds, including

articulated voices. It usually uses magnetic tapes, either wound on a reel or in a

cassette, for storage. In its current form, it records a fluctuating signal by moving

the tape across a tape head that polarizes magnetic domains in the tape, in proportion

to the audio signal. There are many types of tape recorders in existence, from small

hand-held devices to large multi-track machines. A machine with built-in speakers

and audio power amplification to drive them is usually called a ‘tape recorder’. If

this machine does not have the record functionality, it is a ‘tape player’; while one that requires external amplification for playback is usually called a ‘tape deck’(regardless of whether it can record).

The invention of tape recorder has brought about a revolution in the teaching–

learning process. Its main function is recording and reproducing of sound. Microphone,

amplifier and reproducer are its three parts. It is an instrument which is used to

record speeches, songs, and music. It may be played back at any time and any

number of times. Teaching with tape recorder is an extension of a teacher’s work.

The educational utility of tape recorder in education has been highlighted in the following points:

 There is no fixed time schedule for tape recorded programmes and thus,

no changes are required in the school timetable. It can be used anytime and anywhere.

 It helps in supplementing the educational output of radio and television broadcasts and guest lectures.

 Recorded educational programmes can be used for instruction in schools and colleges.

 It helps students in developing oratory skills by repeated practice. Further,

it helps in overcoming poor speech habits and correcting speech defects.

 Tape recorders are immensely used in developing conversation skills,

expression power and techniques of dramatization.

 They are significantly used in teaching specific subjects like music,dramatics and language.

 They are also used in organizations for conducting and evaluating various co-curricular activities.

 They may help in modification of behaviour and for encoding classroom events.

 They can supplement other educational tools like projectors, video players.

A tape recorder is very easy to operate and useful in group teaching as well

as individual learning. It is also easy to erase a recording, if not required.

4.3.4 Computer as a Teaching Aid

A computer is an electronic device that accepts data, performs operations on it in a

sequence (decided by a programme) and gives the resulting output. Computers can

be of various sizes and types like mainframe computers, mini-computers and

microcomputers. Apart from size, computers are differentiated according to their

specifications. These specifications include the amount and type of storage, capabilities

of the Central Processing Unit (CPU), and type and nature of the peripheral

equipment (such as disc storage) that can be connected to it.

A computer has several applications in instructional situations. It is used to

analyse the level of knowledge in entry level students, at the time of enrolment. It is

also used to plan and print individual programmes, monitor a student’s progress and

compile tests and scores. Computers are aid to the instructional process of education.

In terms of technological advancement and educational utility, they have surpassed

all the audio-visual aid material and equipment. The demand for computers is increasing day by day, at all levels of education.

In various forms and at various levels, computer technology has been able to

make a strong impact on education. The advantages of computers in education

include efficient storage and rendition of information, quick information processing,

and the most important benefit being saving of paper.

Some of the characteristic features of application of computers in education are:

 Modern systems of education have been greatly influenced by the usage

of computers. Students find it easier to refer to the Internet for searching

information rather than look for it in books. The process of learning is not

limited to learning from prescribed textbooks, it is much more.

 Computers have played an essential role in promoting education to a large

number of learners. By taking education outside the classroom, this

technology has made the dream of distance learning a reality. It has been

able to bridge geographical barriers in the process of education. In other

words, computer networking has brought physically distant locations closer.

This has benefited all those, who are in the field of education.

 Efficient storage and effective presentation of information has been enabled

by use of computers. There are several presentation software like

PowerPoint and animation software like Flash, which have proved to be

of immense help to teachers while delivering information.

 Computers have the potential to add an element of fun to education. It is a good break from the monotony of ‘chalk and talk’ classes. They can turn out to be a brilliant aid in teaching, if used properly. Computers facilitate

making the process of learning interactive and interesting by audiovisual presentation of information.

 Computers have helped in going ‘green’. They help in saving paper by

facilitating an electronic format for storage of information. There have

been instances where schools have gone far and even collected homework

and test assignments as soft copies and thus saved paper. It is well known

that electronically erasable memory devices can be used repeatedly. They offer a robust storage of data and reliable data retrieval techniques.

Computer technology thus eases the process of learning.

 The Internet can play a significant role in different aspects of education.

Being a colossal information base, it can be used well for retrieval of information on a wide variety of subjects. There is not a single subject

taught to students for which the Internet cannot be used to gather information.

Though computers have contributed in different spheres of education, the most important contribution is in the domain of instruction; in the form of Computer

Assisted Instruction (CAI) and Computer Managed Instruction (CMI). Here, it needs to be emphasized that computers should be used as an educational tool, rather

than a means of education. Nothing can replace interactions between students and teachers.

ALSO READ: Factors Affecting Classroom communication 

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