t8 ohp and transparencies final 090113

Download T8 OHP and Transparencies Final 090113

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EDU topic 8





This topic describes the learning activities associated with the parts and functions of the OHP and manner of its operation. Similarly, an explanation of the advantages and disadvantages is described together with the use of OHP. The title is also expressed on some types of transparencies and preparation technique and good performances. Similarly, the use of playback screen discussed together.


By going through the learning activities of this topic, hopefully you will be able to:

i. know and understand the parts and functions of the OHPii. Understand the proper operation of OHPiii. list the advantages and disadvantages of using OHPiv. understand the types of transparenciesv. learn preparation techniques and transparencies presentation vi. understand variety of screen view and use


8.1 Parts and Functions Overhead Projector 8.2 Handling OHP8.3 Types of Transparencies8.4 Techniques for the Preparation and Transparencies Presentation 8.5 Projection screen8.6 Presentation Using Projection screen


Transparency is the medium that is similar to a 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 projecting images from transparency to white screen (white screen) in a bigger size. Its use is more effective for teachers to convey teaching contents when compared with print and stationary aids. It is very effectively used to clarify things "out of context", concepts, facts, data and visual information.

8.1 Parts and Functions of transparency Projector

Transparency projector is a visual tool that can be used in a normal classroom. This projector is a teaching aid in achieving more effective teaching, where the students will be taught in a way to see and hear.

Diagram 1 : Transparency ProjectorSource : Sharifah Alwiah Alsagoff (1992)

8.2.1 Transparency Projector handling guide

a. Make sure you properly understand the make / brand and functions of projector parts you are using. This may vary from one device to another device.b. You must learn to detect damage to the bulbs so that they can be fixed. Be careful when replacing the bulb. Do not touch it with bare hand because the bulb can be easily damaged.c. Clean the mirror plate inside the projector occasionally.d. Project the image to the wall or a white cloth if there is no screen.e. The transparency Projector unit should be moved using a trolley for easy transfer from one place to another. Switch off the power before moving.f. For a good display, the following must be observed:i. Screen width of 1.5 m for a room for 40 peopleii. Screen is not glossyiii. Getting a little lightiv. Put at the height of 70 cm from the floorv. Tilt 45 degrees to avoid the effects of distortion (keystone)vi. Make sure the screen is uprightvii. Do not block by users so that can be seen by all students.viii. All writings and drawings must be in accordance with the appropriate size.ix. Use a straight pointed indicator and show something on transparency rather than on the image on the screen.

8.2.2 Advantages and disadvantages of using OHP

Advantages of the Use of OHP transparencies are as follows:a. In the process of delivering instruction, teachers can incorporate the use of the blackboard, and oral presentation.b. Pictures or images of transparencies can be screened without switch of the light..c. Transparency can be used repeatedly and delivery can be done in a more organized and systematic manner.d. Teachers deal with students or audience during delivery. This will help teacher to have easy control.e. Transparency is easy to use, cleaner than with the use of blackboard and chalk.f.Use OHP and transparency will make teaching and learning more effective. Comments and new information can be added in the diagram or in pictures that are available in transparency; i. using color, illustration and animation.ii. images or pictures can be blown out or reduced according to the needs of pupils.iii. save time and speed up the delivery.g. OHP projector can be easily handled and teachers do not need in-depth technical knowledge to use it.h. By using transparencies, teachers are able to deliver relevant information and facts in a systematic manner.

8.3 Types of transparencies

8.3.1 write- oni. made of acetate and polyesterii.Has 3 levels of thickness 0.08 mm, 0.1 mm and 0.12 mm. General purpose transparencies commonly use 0.1 mm thick.iii. Transparency has two sizes of 260 mm x 260 mm and DIN A4 (210 mm x 297 mm)iv. Using water-based pen or spirits based pen.

8.3.2Thermal (infra-red)

a. Processed by 'Transparency Maker machines b. Have different background and color as "Black On Clear '(black image with clear background.), 'Black On Color' (black image with colored background), 'Color On Clear' (colored image with clear background)c. Carbon-based Materials such as news paper cuttings, 2B pencil, dust based photocopying materials, and laser printer dust based print from.d. thermal transparencies preparation guide as follows:i. Rotate the adjustable knob to the number 3 to 6 so that the picture produced will be clear.

ii. Place the base material under thermal transparencies where the notches in the top right corner at the top.iii. iii. Insert base and thermal material into the machine 'maker' Transparency 'and let the machine suck up the image of material transferred to the transparent base material.

Diagram 2 : Proses Thermal process (Insfra-red)Source : Sharifah Alwiah Alsagoff (1992)

8.3.3 Photocopying

a. Processed using a photocopy machine (plain paper Copier)b. Base material is placed at the top of the mirror and put transparencies in the tray as as making a photocopy.c. Picture color or black colored pictures can be transferred but will be black and white.

8.3.4 Ink-jet Film

Ink-jet Film can be used directly on ink-jet printers such as Canon and Epson printers. Base material can be prepared by using a computer and copy direction as you make on paper copiers.

8.4 Techniques for the Preparation and Presentation Transparencies

8.4.1 Production Techniques Transparency

a. Write-on technique All documents written or drawn together by hand or machine directly on transparency film. The transparencies is broadcast directly to the audience.

b.window techniqueHave several windows that cover certain parts of the surface of transparencies. When used, the windows will be opened one by one like the home window to display the contents or images.

Diagram 3 : window techniqueSource : Razali Nor (1996)

c. Striped techniques

This techniques have bands either horizontally or vertically. Its opened only one way not as open windows technique in both directions. Only 3 to 4 strips in a transparency.

d.Overlapping techniques (layered)Consists of films that are placed directly on the basis of a fixed frame and some additional film placed on the sides of the frame.

Diagram 4 : Overlapping techniquesSource : Razali Nor (1996)

e.Round techniqueIt seeks disclosure of or part by part to reveal anything needed. It can be made in the cover inserts (vertical, horizontal or diagonal or rounded cap. Spherical cap can be made by means of a pinned in the middle.

f. Animation techniques It uses plastic sheets polarising fixed upon certain parts of the image that is on the transparencies. During use of the device is placed on the lens polariser OHP bay. The image will appear to move when the image is pulled or moved.

Activity 1

Do you know the types of transparencies used? Navigate the Internet to identify other types of transparencies. List down types of transparencies and their characteristics.

8.4.2 Transparency Preparation Principles

i. Plan appropriate methods or techniques before starting to make transparency with existing equipment.ii.ii. Analysis of the information to be communicated carefully in terms of use, objectives and content.iii. Determine the presentation format. Longitudinal or vertical format. Avoid obscure format i. Make sure each creation (graphics, statements) are within 2 cm from the edge of the transparent material.ii. Clarity of alphabets depending on the type, size, spacing between letters and spacing between rows.iii. The smallest image on the screen should be 2:56 cm in height for every 8 meters distance display.iv. Use a larger font for headings and sub-headings.x. Restrict writing between 6 and 7 lines in a piece of transparency.xi. Use 7 to 10 words on every sentence.

8.5 Playback screenPlayback screen is another key requirement for using the playback media. There are two categories projection screen with media. The first category is translucent screen which is rear screen. This type of screen view on both sides. Spectators can watch from the back and from the front of the screen. The second category is the front viewing screen, often used in schools. Playback screen is made up of several types of surface reflection. It varies in size, materials and functions. There are those who use some form of electric and manual.Playback screen type frequently used in schools consist of the following types of playback screen:

8.5.1 Matt type playback screen

This type of screen consist of thick cloth or canvas with white and smooth surface. This type of screen reflect light much less than the other screen. Matt screen view type is suitable for use in rooms that are short and wide.

8.5.2 Silver Matelled type screen

"Silver Matelled" scr