PRINT AND NON-PRINT MEDIA
4c v). Examine the place of Overhead projectors and transparencies in the teaching process.
188.8.131.52 Overhead projector and transparencies
Overhead transparencies may be created from clear acetate, photographic film, or any of a number of other transparent materials capable of being imprinted with an image. The materials range from single, simple transparencies to elaborate sets with multiple overlays. The OHP is a useful visual aid to support mass instruction. It has largely replaced the chalkboard. It has the following advantages:
- The teacher can use it while facing the class unlike the chalkboard
- It can be used to show prepared materials which can be used over and over again
- It is clean, quiet, and user-friendly and requires minimum technical skill apart from replacing the bulb
- It requires no room darkening thus allowing pupils to take or make notes simultaneously
The overhead projector (OHP) is used to project transparencies that are similar to large slides. It projects a large picture. transparencies can be used to visually present concepts, processes, facts, statistics, outline, and summaries to small groups as well as large groups. A series of transparencies can be used to systematically present a well-planned lesson. Presentation using an OHP can be improved by:
- Using a pointer on the transparency to direct attention to a detail
- Using a felt pen or a special pencil to add details or mark points on the transparency during the presentation.
- Control the rate of presenting information by covering a transparency with paper and exposing the data when you are ready to discuss each point.
- Superimposing additional transparent sheet as overlays to add complexity to the concept present in the base transparency. Moving overlay sheets so as to rearrange elements of a diagram.
- Simultaneously project other visual materials (on slides or in motion pictures) that illustrate or apply the generalizations shown on the transparency. Some of the methods of preparing transparencies include :
- Using felt pens
- On thermal film using a thermal copier, this is a good method of preparing one color transparency from single sheets
- On electrostatic film using an electrostatic copy machine, the final product is not a good as from the other methods.
- On diazo film using a diazo printer and developer. This is an excellent method for preparing color transparencies and requires translucent originals.
In preparing transparencies, remember to:
- Not to crowd the transparency with too much information
- To make characters of a suitable size (minimum 6 mm. in height)
- To provide satisfactory space between lines of text
- To make lines thick enough for easy reading
- To select the color and their intensity for strong images during projection.
For effective use of transparencies the following utilization checklist would be useful:
- Use the same frame size for all your transparencies
- Number the transparencies sequentially in the order in which they will be used
- Place your notes on the frame of the transparency
- Focus the image so that it fills the screen
- Add meaningful details to the transparency as needed
- Direct student attention to parts of the transparency
- Overly new information in steps
- Shift the student’s attention back to you by switching off the OHP