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
