Audio - Visual Aids

Ø            Audio – Visual Aids:

1.                 Glass Slide Projector:

-         Simple device

-         Project pictures form a glass slide on a wall or a screen

-         Small size picture is seen by whole class

-         Not very costly

-         Readymade slides are available

-         Practical training is require

-         Slides covered with thin layer gum may be used

2.                  Over Head Projector / Lecture Table Projector:

-         Self operated by the teacher

-         Advantages:

1.                  Face pupils while interacting

2.                  To Operate machine is very easy

3.                  Screen is over head of the teacher which helps students to see the content

4.                  Point out important features of  the pictures by indicating with pencil

5.                  Changing of slide is easier

6.                  Teacher can see the slide and explain.

3.                  Epidiascope:

-         Transparent as well as opaque objects can be projected without tearing it off.

-         No slide is needed

-         Structure:

1.                  Light from a lamp falls on the opaque object

2.                  Plane mirror at 45 dgree over the object reflects light so that it passes through a projection lens. Magnified image can be seen on the screen

-         Purposes:

1.                  To throw an image of an opaque body it works as episcope

2.                  To project slide by the movement of a lever it works as diascope

Thus Episcope + Diascope  = Epidiascope

-         Advantages:

1.      Projection of original colours

2.      Projection & explanation together

3.      Handling of lesson as desires

-         Precautions:

-         Complete dark room require

-         Objects should not exposed to heat of the lamp for a long time

-         Practical Training needed

4.                  Filmstrip Projector:

-         One strip or piece of still film is prepared

-         Less expensive

-         Less bulky cannot broken easily

-         One film strip – one topic – 40 to 100 separate pictures can be shown

-         Available on loan free of charge –

-         Sources of Film :

1.                  Central film library, central institute of educational technology, NCERT

2.                  SCERT

3.                  Extension service department of college of education

4.                  United states information service, New Delhi

5.                  British High commissioners office, New Delhi

6.                  Other Foreign Embassies

Material & preparation of film strip

7.                  Cellulose Acetate film 16mm or 35 mm wide

8.                  Length 2 to 5 feet

9.                  Pictures are concerning one topic

10.              Arranged in a definite order

Working of film strip projector:

11.              Strip is inserted from the side instead of from above

12.              Examined film carrier before use

13.              Toothed wheels clamp the edges of the strip

14.              Desirable to discover at which end of strip it is to begin

15.              Pictures are allow to move

16.              Roll of film strip is placed above the carrier & it flows downwards

17.              Focusing by moving the objective lens

18.              Easy to operate by hand

19.              Teacher can stop wherever he likes to explain & discuss about particular aspect of topic.

Science films can be shown for two purposes:

20.              Shows various applications & uses of science in the world in general ways. It can be shown to large group, whole school. Create scientific atmosphere.

21.              Supplement the classroom. Shown with definite purpose to serve as teaching aids.

Examples of films:

- How to use a microscope

- Manufacture of H₂SO₄

- Use of atom

                 Advantages of Motion Pictures:

22.              Present certain meanings involving motion

23.              Compel attention

24.              Help clarify the time factor in any operation or series of events

25.              Bring the past & the distant to the classroom

26.              Enlarge & reduce the actual size of objects

27.              Present a process that cannot be seen by the human eye even by microscope & telescope

28.              Provide an easily reproduced record of an event

29.              Reach a mass audience at a low average cost per person

30.              Build a common denominator of experience

31.              Offer a satisfying aesthetic experience

32.              Give an understanding of relationships of things, ideas & events

Types of Film Projector

33.              Standard Theoretical Project for 35mm films

34.              Portable projector for 16mm films

1.                  It is used in school

2.                  Less costly

3.                  Lighter in weight in size

4.                  Easy to carry & operate

5.                  Brands used are “RCA” , “ Bell & Howells”

The projector :

1.                  Complicated than slide projector

2.                  Training require to operate

3.                  Optical parts are same as in a magic lantern

4.                  Strong source of light, a reflection, a picture

5.                  Carrier & Projecting lens

6.                  Arrangement of continuous flow of film

Steps in showing film:

1.      Preparation:

35.              Projector should be in working condition

36.              Room should be dark

37.              Sitting arrangement for the students

38.              Teacher should see film in advance

39.              Read notes given in the catalogue related to the film

40.              Complete background of the contents of film should be given to the students before screening of the film

2.      Screening Film:

41.              Calmly & without interruption

42.              Do not create cinema hall atmosphere

43.              Observe every projection minutely & carefully

44.              Should not take the show as mere recreation

3.      Follow up:

45.              Invite comments, questions, doubts and healthy discussion

46.              Questions to be asked in examination

47.              Encourage to write articles for the wall magazine or printed magazine

5. Micro Projector:

-         Used in the biology department

-         Essential for showing microscopic slides, small living specimens & growth of crystals

-         Image on vertical screen

-         Dark room require

Limitation:

- Size of image is more than one foot long & magnification is 20 times than image will not be bright enough