OVERHEAD PROJECTOR

Meaning

• Overhead projector is a device for projecting a

matter, which is written or drawn on

transparent sheet of acetate on to a screen.

• It is the cheapest projecting aid currently

available

Preparation of OHP Transparencies

1.Use a standard size of acetate sheet measuring

18cm x 22.5cm.

2.OHP markers are available in two types;

temporary and permanent.

3.Transparencies must be clearly written with at

least 8mm size letters either free hand or by

transfer letters or template, etc.

4.The best colours to use to write on transparencies

5.Information on the sheet to a minimum and make

the image large enough

6.Avoid copying information from a printed book

or journal page or a type written sheet.

7.Transparencies can be very creative, especially if

you have artistic help.

Effective Use of Transparencies

1. The overhead projector and the screen should

be positioned well.

2. OHP should be on, with the transparency in

position as and when required.

3. Transparent colour Perspex arrow heads or

pointed objects such as pencils placed on the

transparency at the platform are recommended

for pointing.

4. Human silhouettes are irritating

5. It is best not to project the entire transparency at the very beginning

6. Never leave a visual on the screen after a point has been discussed.

7.May radiographs can be projected successfully with the overhead projector

8.Transparencies can also be made with

overlays-additional acetate sheets can be placed

over the base transparency to add new features or

colours.

9. By using silhouetting effect, opaque objects

can be projected

10.not blocking the students’ view.

11.Transparencies can be used similarly to a

chalkboard

Advantages of Overhead projector • Transparencies can be prepared before hand

a) to save class time and b) to help organize and illustrate content.c) Diagrams and drawings can be drawn or copied on to transparencies.

• Concepts can be illustrated. • Lectures can be outlined. • Cartoons can be projected for interest and

illustration.

• Teachers can face the students while using it.

• The room does not have to be dark, although it

is often helpful to dim the lights around the

screen.

• The projector is easy to use, requiring only

manipulation of an on-off switch and a focus

knob.

• It is the cheapest of all projected audio-visual,

photocopies of transparencies may be handed

to the students if desired.

• Transparencies may be reused by employing

washable colour markers or can be preserved

for future use by employing permanent

markers.

• Using transparencies is less pollutant and less

strenuous than using a chalkboard.

• Transparencies may be referred to back and

forth in the same or in different sessions.