Over head projector

An overhead projector (OHP), like a film or slide projector, uses light to project an enlarged image on a screen, allowing the view of a small document or picture to be shared with a large audience.

In the overhead projector, the source of the image is a page-sized sheet of transparent plastic film (also known as "foils" or "transparencies") with the image to be projected either printed or hand-written/drawn. These are placed on the glass platen of the projector, which has a light source below it and a projecting mirror and lens assembly above it (hence, "overhead"). They were widely used in education and business before the advent of video projectors.

1. SUSMITA HALDER M.SC. NURSING 1 ST YEAR CON BSMC, BANKURA OVER HEAD PROJECTOR

2. DEFINITION Overhead projector is a device for projecting a matter, which is written or drawn on transparent sheet of acetate on to a screen.

3. It projects tranperancies with brilliant screen images suited for use in lighted room The teacher can draw diagrams on the transperancy while he teaches, these are projected simultaneously on the screen of the over head projector

4. Purpos es of Overhead Projector To develop concepts and sequences in a subject matter area . each component part can be presented as the teacher senses the students’ readiness for the next step use To test students’ performances, while others classmates observe. To show relationships by means of transparent overlays in contrasting color.

5. Purpos es of Overhead Projector To make marginal notes on the transparencies for the use of the teacher that can be carried without exposing them to the class, when projected. As a recording device for presenting minutes of a group discussion visually. To give illusion of motion in the transparency To show statistics and other graphs of mortality and morbidity rates of various diseases.

6. USING AN OHP

7. OHP Transparencies

8. OHP Transperancies

9. Types of T ransparency

10. Articles Required for preparing Transparency

11. Guidelines for making effective transparencies

12. Preparation of OHP Transparencies Use a standard size of acetate sheet measuring 18 cm -22.5 cm. OHP markers are available in two types; temporary and permanent. Temporary markers have soluble ink and written matter can be wiped off with the help of a damp cloth. Permanent markers are oil, spirit or wax based and their writing is preserved for long time. One may prepare reusable transparencies with permanent OHP markers. Additions and alteration during teaching should be made with water soluble OHP markers so that the same are wiped off after use. If you want to reuse the transparency sheet later for another purpose, be sure to use a marker with soluble ink. Transparencies must be clearly written with at least 8 mm size letters either free hand or by transfer letters or template, etc. A transparency which can be clearly read from a distance of 2 m should project well for a classroom 6 m deep. Transparencies should be patiently prepared with bright harmonizing or contrasting colors, legibly and systematically. There should be no more than six words in each line and no more than eight lines in each transparency. Put margins appropriately. Of the various types of visuals, diagrams, schematics, cue words, cartoons and graphs make better visual for the OHP.

13. Preparation of OHP Transparencies The best colors to use to write on transparencies are black, blue and green. Use red sparingly. It is not a color that project well. Whether you are drawing the image on the transparency or copying it from a printed page, keep the amount of information on the sheet to a minimum and make the image large enough so that students in the back of the room will be able to see it. Avoid copying information from a printed book or journal page or a type written sheet. Such pages present too much information for the students to take in and the print is usually too small for them to see easily. If you want to type some information on to a transparency, type it on paper first, enlarge the type on a copier with an enlarging function and then make a transparency by taking photocopy of The material. Transparencies can be very creative, especially if you have artistic help. If you have produced a transparency worth saving for future classes you may want to mount it in a cardboard frame that gives it some protection, enables you to handle it without touching the acetates and reduces glare around the image.

14. Method of Preparing

15. Masking and Overlay Techniques

16. Specific Techniques Used in OHP

17. Points to remember during OHP Presentation

18. Advantages of Overhead Projector

19. Disadvantages of Overhead Projector

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