This document discusses the use of overhead projectors (OHP) as an educational audiovisual aid. It defines an OHP and its parts, and outlines how to effectively design and present materials using transparencies. Key advantages of OHP include portability, low material costs, and maintaining eye contact with students. Potential disadvantages are the need for a power supply and spare bulbs in case of malfunctions. Proper use of OHP can engage students and enhance learning.

1. CLASS -8 -
EDUCATIONAL AIDS
PROJECTED AIDS- OHP
D.KAVITHA
ASSOCIATE PROFESSOR IN NURSING
DEPARTMENT Obs& Gyn
MPG&RIHS,PUDUCHERRY
KAVITHA DURAIRAJ, ASSOCIATE PROFESSOR 1
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2. PROJECTED AIDS
2KAVITHA DURAIRAJ, ASSOCIATE PROFESSOR

3. INTRODUCTION
 Rapid contribution of science and technology
in the development of newer projecting
audiovisual aids has revolutionized the field of
audio visual aids.
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KAVITHA DURAIRAJ, ASSOCIATE PROFESSOR

4. DEFINITION OF PROJECTED
VISUAL AIDS
 Projected visual aids are pictures shown upon
a screen by the use of a certain type of
machine.
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KAVITHA DURAIRAJ, ASSOCIATE PROFESSOR

5. ADVANTAGES OF PROJECTED
AV AIDS
 Provides greater enjoyment in learning
 Stimulates more rapid learning
 Increases retention: larger percentages and
longer retention
 Compels attention
 Enlarges or reduces actual size of objects
 Brings distant past and the present into the
classroom
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KAVITHA DURAIRAJ, ASSOCIATE PROFESSOR

6.  SLIDES
 OHP
 FLIMS
 TV/VCR/VCD/LCD
 CAMERA MICROSCOPE
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KAVITHA DURAIRAJ, ASSOCIATE PROFESSOR

7. OVER HEAD PROJECTOR-
INTRODUCTION
 Overhead Projector was created by Jules
Duboscq, in 1870s.
 Used during the Second World War
 Used as a teaching tool since 1950s.
 Become popular easy to used
 Provides an interactive environment for
educators.
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KAVITHA DURAIRAJ, ASSOCIATE PROFESSOR

8. OVER HEAD PROJECTOR
 Over head projector helps in the projection of
transparencies with brilliant screen images
suitable for use in a lighted room. It is a very
vital teaching aid and has made teaching
simple and easy
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KAVITHA DURAIRAJ, ASSOCIATE PROFESSOR

9. DEFINITION
 Overhead Projector: machine designed to
project an image, text, and drawings onto a
small screen or whiteboard
 Transparencies: pages transparent and
flexible used to place information and images
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KAVITHA DURAIRAJ, ASSOCIATE PROFESSOR

10. PARTS OF OHP
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KAVITHA DURAIRAJ, ASSOCIATE PROFESSOR

11. Parts of over head projector
1. Metal box with a 1000w bulb for an indirect
projection / 600w Halogen Lamp for a direct
projection and a concave reflector
2.Transparent writing place 25x 25cm
3. Fresnel lens is used to form a converging
beam of light . Which illuminates the stage
area uniformly and converges to the projected
lens
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KAVITHA DURAIRAJ, ASSOCIATE PROFESSOR

12. 4. The projection lens is used to form
converging beam of light . Which illuminates
the stage area uniformly and converges to the
projected lens
5. A surface aluminized mirror / very thin flat
mirror serves to rotate the path / light by 90˚
6. Small exhaust / cooling fan in the projector to
blow out the excess heat produced by the bulb
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KAVITHA DURAIRAJ, ASSOCIATE PROFESSOR

13. 7. Fresnel lens protected by a glass plate.
8. Knob – the projection distance can be
adjusted in accordance with the desired
picture size
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KAVITHA DURAIRAJ, ASSOCIATE PROFESSOR

14. Accessory structures
 Screens may be aluminum coated .
 Glass bead / flat white screen
 Stabilizer to prevent voltage fluctuation
 Pointer
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KAVITHA DURAIRAJ, ASSOCIATE PROFESSOR

15. How the OHP can be used in
different Instructional Situation
 Expository teaching of virtually any type
 Group learning situations
 Enabling members of a group to display
material that they themselves have produced
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KAVITHA DURAIRAJ, ASSOCIATE PROFESSOR

16. CONT….
 To present activity plan or objectives
 To show tables

 To systematize the information to be conveyed
 To list brain-storming idea
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KAVITHA DURAIRAJ, ASSOCIATE PROFESSOR

17. OHP transparencies
 Size – 7x7(or) 10 x10”( 25x25cm)
 MATERIALS CAN BE PROJECTED

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KAVITHA DURAIRAJ, ASSOCIATE PROFESSOR

18. GUIDELINESS-HOW TO USE
THE OHP
 Located it in a place
where everybody
can see the screen.
 Arrange the
projector and screen
in a way to minimize
it. It should have
appropriate angles
in horizontal and
vertical planes.
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KAVITHA DURAIRAJ, ASSOCIATE PROFESSOR

19. CONT…
 Adjust the distance
from projector to
screen so the image
fills the full area
 Make sure the
acetate and open
head surface are
clear and free of
dust or dirty
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KAVITHA DURAIRAJ, ASSOCIATE PROFESSOR

20. STANDARDS IN USING OHP
 Make the text,
illustrations or pictures
in your transparencies
big enough
 Schematize: present
essential points, one
transparency every 2 or
3 minutes
 Use a pointer to
emphasize points on
the acetate
 Plan for a dramatic
presentation
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KAVITHA DURAIRAJ, ASSOCIATE PROFESSOR

21. CONT…
 Check visibility; do
not block the screen
 Plan your narration.
 Turn on the lamp
only if there is a
transparency on the
projector
 Put off the projector
for prolonged
explanations, or when
it is not needed
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KAVITHA DURAIRAJ, ASSOCIATE PROFESSOR

22. DESIGNING OHP
TRANSPARENCIES BASIC
PRINCIPLES
 There two basic
Principles:
1. Do not try to put
too much
information on a
single
transparency.
2. Use a clear,
systematic layout.
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KAVITHA DURAIRAJ, ASSOCIATE PROFESSOR

23. PRODUCING COMPUTER
GENERATED OHP MATERIALS
 Use computer to design and produce
OHT
 Create both alphanumeric and
graphic materials and print them out
in OHP transparency form - in full
color, and with whatever size of
lettering is wanted
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KAVITHA DURAIRAJ, ASSOCIATE PROFESSOR

24. DISPLAY TECHNIQUES
 Progressive
Disclosure Involves
covering up all or
part of the material
on a given
transparency, and
progressively
revealing the
material as the
presentation
proceeds
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KAVITHA DURAIRAJ, ASSOCIATE PROFESSOR

25. Display techniques
b) Framing
Transparencies
Essential
information placed
visible for your
audience and notes
written for the
teacher’s support
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KAVITHA DURAIRAJ, ASSOCIATE PROFESSOR

26. Display Techniques
c) Use of overlays
Whole area of
transparency is
revealed from the
start, with additional
information being
added to the original
display by
superimposing
further
transparencies on
the original.
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KAVITHA DURAIRAJ, ASSOCIATE PROFESSOR

27. DISPLAY TECHNIQUES
c) Use of Overlays
1. To lay separate
transparencies
2. Make use of hinged
overlays
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KAVITHA DURAIRAJ, ASSOCIATE PROFESSOR

28. Tips to use OHP Effectively
 1.Just write key points on
transparencies
 2.Keep transparencies simple -
6X6Rule
 3.Use 18 point type- no more than two
type styles
 4.Mix upper and lower-case letters for
easy readability
 5.Do not use exclamation marks, they
look like number one.
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KAVITHA DURAIRAJ, ASSOCIATE PROFESSOR

29. Cont…
 7. Do not turn off all room lights
 8. Turn projector lamp off during
discussions
 9. Never stand anything between the
projection and screen
 10.Give people time to read
 11.Talk to your listeners not the screen
 12. Before moving wait for period time to
cool Down - bulb may explode.
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KAVITHA DURAIRAJ, ASSOCIATE PROFESSOR

30. FOR PREPARING A
TRANSPERENCY
 Six lines per transparency
 • Six words per line
 • Six mm smallest letter size
 • Six cm (3+3 on each side) margin
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KAVITHA DURAIRAJ, ASSOCIATE PROFESSOR

31. MATERIALS
 a)Transparencies
 b)Markers
 c)Ruler
 d)Cleaning supplies
 e)Bulbs
 f) A pointer
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KAVITHA DURAIRAJ, ASSOCIATE PROFESSOR

32. METHOD OF USING OHP
 Place the OHP on a stable table with the
objective lens
 facing the screen behind the teacher.
 Put the cord plug into power wall socket.
 Switch on the blower first and then the bulb.
 Place transparency on the glass top.
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KAVITHA DURAIRAJ, ASSOCIATE PROFESSOR

33.  Move the objective lens and mirror assembly
up and down to get the image in focus on the
screen.
 Explain about the material on the
transparency from behind OHP with a strong
pointer.
 The handle of the teacher should not come on
the slide.
 Make your points short and simple
 Remove what is not needed.
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KAVITHA DURAIRAJ, ASSOCIATE PROFESSOR

34. SOME DO’S AND
DON’T’S WHILE USING
THE OHP
34 KAVITHA DURAIRAJ, ASSOCIATE PROFESSOR

35. DO’S
 Focus and position image before presentation
 Stand to the side of the screen
 Turn off projector when not in use
 Letters the larger the better
 Use colour to attract attention
 Put captions on top.
 Have images in to two-thirds of visual position
image at the top of the screen
 Use pen or ruler to point
 Use upper and lower case letters
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KAVITHA DURAIRAJ, ASSOCIATE PROFESSOR

36. DON’T’S
 Walk or stand in front of the screen.
 Leave the projector on when you’ve talking
about
Something
 Write closely on the whole of the transparency
sheet
 Have images type-written or too small
 Use black and white visuals only
 Use finger to point
 Use only capital letter
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KAVITHA DURAIRAJ, ASSOCIATE PROFESSOR

37. CHECK LIST FOR EFFECTIVE
USE OF OHP
1. BEFORE THE LESSON
 Position the screen
 Obtain correct image by moving machine
backward/ forward in relation to the screen
 Focus image sharply
 Place masking sheet to hand
 Place the transparencies in correct order
 Check table and head for dust
 Ensure that spare lamp is available
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KAVITHA DURAIRAJ, ASSOCIATE PROFESSOR

38. DURING LESSON
 1.switch off when
Placing transparency on table
Removing transparency
Point has been explained
 2. use pointer to indicate
 3. use mask to reveal the points in a step by
step
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KAVITHA DURAIRAJ, ASSOCIATE PROFESSOR

39. AFTER LESSON
 Donot move the OHP while lamp is HOT.
 Never disconnect from main supply while the
fan is operating
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KAVITHA DURAIRAJ, ASSOCIATE PROFESSOR

40. ADVANTAGES OF USING OHP
 It is portable
 Get transparency materials in low cost
 Located in front of the room
 Used in a room with normal lighting
 It is simple to operate
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KAVITHA DURAIRAJ, ASSOCIATE PROFESSOR

41. ADVANTAGES OF USING
OHP
 Used as a chalkboard or market board
 Modify transparencies during the presentation
 You can write without turning your back
 Maintain eye contact
 Audiences can follow handout or take notes
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KAVITHA DURAIRAJ, ASSOCIATE PROFESSOR

42. DISADVANTAGES OF USING
OHP
 It requires a power supply
 Needs suitable surface about four square feet
 Need spare bulb in case unexpected events
 Many users do not give sufficient thought to
the production of their display material
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KAVITHA DURAIRAJ, ASSOCIATE PROFESSOR

43. CONT…
 Tendency to include too much information in a
single frame
 Teachers or lectures overuse the OHP
 Difficult to transport because of its weigh
 Cost of materials required to operate them
 Used with small audiences.
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KAVITHA DURAIRAJ, ASSOCIATE PROFESSOR

44. CONLUSION
 OHP is a useful tool to project information for a
small audience.
 It provides some advantages using it as well
as some disadvantages.
 There are some usage principles teachers
should follow to make its use effective.
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KAVITHA DURAIRAJ, ASSOCIATE PROFESSOR

45. KAVITHA DURAIRAJ, ASSOCIATE PROFESSOR
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