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TOPIC 8: OHP AND

TRANSPARENCY

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By going through the learning activities of this topic,

hopefully you will be able to:

i. Know and understand the parts and functions of theOHP

ii. Understand the proper operation of OHP

iii. List the advantages and disadvantages of using OHP

iv. Understand the types of transparencies

v. Learn preparation techniques and transparencies

presentation

vi. Understand variety of screen view and use

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Transparency is the mediumthat is similar toa slide which is classified as teaching aids in

the form of projection view.

It requires a machine running at top-level(Over Head Projector - OHP) for projectingimagesfrom transparency to white screen(white screen) in a bigger size.

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Its use is more effective for teachers toconvey teaching contents when compared

with print and stationary aids.

It is very effectively used to clarify things "outof context", concepts, facts, data and visualinformation

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A visual tool that can be used in classroom

Effective way to teach, where the studentscan see and hear

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Click on this

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ADVANTAGES

Can be incorporated during

lesson Pictures or images of

transparencies can bescreen without the switchof light

Can be use repeatedly To have easy control of the

class Easy to use

DISADVANTAGES

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Write on Thermal (infra red)

Photocopying Ink jet film

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Plan appropriate methods or techniques beforestarting to make transparency with existing

equipment

Analysis of the information to be communicated

carefully in terms of use, objectives and content.

Determine the presentation format. Longitudinal orvertical format. Avoid obscure format

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Make sure each creation (graphics, statements) arewithin 2 cm from the edge of the transparent

material.

Clarity of alphabets depending on the type, size,

spacing between letters and spacing between rows.

The smallest image on the screen should be 2:56 cmin height for every 8 meters distance display.

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Use a larger font for headings and sub-headings.

Restrict writing between 6 and 7 lines in a piece of

transparency.

Use 7 to 10 words on every sentence.

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Two categories of projection media:

Translucent screen (rear screen)

Front viewing screen (*commonly used in school) Matt type playback screen

Silver Metalled playback screen

Glass beaded type playback screen

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Matt Type playback screen

Consist of thick cloth or canvas with white and

smooth surface. Reflect light much less than the other screen.

Suitable for use in rooms that are short and wide.

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Silver Metalled playback screen

capable of giving a good reverse light and has

good quality projection image

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Glass beaded type screen

gives much brighter picture or image than Matt

type screen.

White surface is sprayed with glass powder thatclosely resemble sandpaper.

This type of screen can be used in a narrow and

long room.

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The most ideal location of the screen is at theright side of the teacherin the classroom.

(facilitates the movement of teachers to use theOHP, record the information on the chalkboardwithout opening or closing the screen)

Screen are placed on a higher level

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If it is not at right angles to its image will beknown as "keystone effect" (keystone effect),

which makes viewing distorted.

"keystone effect" can be corrected byensuring that the on-screen display imageview is at right angle.

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Correcting the "keystone effect", theplayback screen position must also be at an

appropriate distance.

This means that the distance between thescreen and the audience in the back row arepreferably at a distance of 20 meters.