Projected aids

 ASSIGNMENT

ON PROJECTED AIDS

Submitted by,

VIJI MOL. M. V

Christ Nagar College of Education

1.INTRODUCTION

Projected aids are much helpful in the teaching learning process. So teachers should know about these aids is very essential in the present situation. Projected aids can give first hand experience by looking at concrete thing, living specimen, handling apparatus, and actual demonstration, etc. It motivates students mental and physical activity and time consuming. Projected aids are very helpful to bring a change in the atmosphere in the class. It makes learning effective and durable. By referring books and websites we can gather information about projected aids.

(Online.WWW.Slideshare.net)

2.PROJECTED AIDS

Projected aids include slides, film strips and film. The projection of these aids involves various types of equipment beginning from the simple magic lantern to the complicated sound film projectors . Projectors can be of three types:

(1) Direct projections

(2) Indirect projection

(3) Reflected projection

3.ADVANTAGES OF PROJECTED AIDS

1. A large group can study picture at one time
2. Magnification is possible which often helps the audience to get across an idea by presenting more details.
3. Original pictures can be reproduced to make several sets available simultaneously
4. Concentrated attention can be expected when visual distraction in the room are moved because of dark room
5. Film, strip, slides etc can be easily be stored and if handled with care, can last quite long.

4.DISADVANTAGES OF PROJECTED AIDS

1. The equipments are very expensive
2. Equipment are not available all over the country.
3. Lot of upkeep and maintenance is required continuously for the equipment, which is often difficult to provide, Specially in smaller cities and towns.
4. Projection is a group technique and , therefore, may not allow enough time for individual study
5. While projecting , the room has to be made dark and therefore, the people can’t take down notes.However it can be overcome by fitting overhead light focusing on individual desko.

5,PROJECTORS

5.1 OVERHEAD PROJECTOR (OHP)

This is a device that can project a chart, a diagram, a map , a table , anything written on transparent plates upon a screen. This makes the screen illuminative and impressive. It also saves a great deal of the teacher time used in drawing or writing them. These transparencies can also be preserved by the teacher for future display while taking up the same topic.

It uses the principle of indirect projection. In this, the projected image is obtained behind and over the head of the instructor. Making use of lens of short focal length and two mirrors to reflect the picture on the screen , the overhead projector can be placed in front of the groups. It shows transparencies of slides of 18”x 10”’ size.

Normally overhead projectors are composed of a projection lamp to act as a source of light, condensing lenses to concentrate all the light into usable beam, a polished mirror and lens assembly and a blower for cooling the system. OHP should not kept on continuously for long periods.

5.1 (1) Advantages of OHP

1. A large image in a minimum projection distance is obtainable.
2. Permits the instructor to face the class as he writes or indicates points of importance on the transparency.
3. Projected image obtained could be seen even in a lighted room.
4. Simple and convenient to operate the equipment.
5. Flexible material can be prepared easily by different methods. It can be used in different methods. It can be used in different ways for writing and presentation of charts etc.
6. Transparencies are securable.

5.1 (2) Disadvantages of OHP

1. The projector is expensive and cumbersome.
2. It requires electricity, special pen and acetate or plastic transparencies.
3. Spare parts may be difficult to obtain and expensive.
4. Light from the projector in the trainer’s eye may be unpleasant.

5.2 L C D

Liquid crystal display (LCD) projectors usually contain three separate LCD glass panels , one each for red, green and blue components of the image signed being fed into the projector. As light passes through the LCD panels, individual pixels can be opened to allow light to pass or closed to block the light , as if each little pixel were fitted in a venetian blind. The activity modulates the light and produces the image that is projected onto the screen. And for larger conference rooms that require higher light output and greater connectivity. LCD technology holds a commanding lead.

5.2 (1) Advantages of L C D

1. It has historically delivered better colour saturation than from a DLP projector.
2. It also delivers a somewhat sharper image than DLP at any given resolution.
3. LCD is more light efficient ie, LCD projectors usually producers significantly higher ANSI lumen outputs than do DLP’s with the same wattage lamp.

5.2 (2) Disadvantages of L C D

1.Visible pixilation or “screen door effect” because it looks like you are viewing the image through the screen door.

2.Lack of impressive black levels and contrast , which are vitally important elements in a good video image.

3. Long term image degradation.

6. CONCLUSION

Projected aids make learning more permanent. They offer a reality of experiences which stimulate self activity on the part of pupils. Develop continuity of thought; this is especially true of motivation picture. Overhead Projectors and LCD are the most widely used projected aids. They have high degree of interest for students and help to develop scientific attitude and get a training in scientific method. It is one of the most convenient, easy and natural way of learning.

REFERENCES

• Mathew and Molly (2006), “Science education theoretical bases of teaching”, Trivandrum , Rainbow publication
• Slideshare.Net
• http://sol.du.ac.in