1. ADVANTAGES OF OHP

2. brightness

3. 2. Direct eye-contact

4. 3. Ease of use

5. 4. Abundance of materials

6. 5. Manipulable

7. 6. Availability of materials

8. 7. Self-prepared materials

9. 8. Advance preparation

10. 9. Impact on attitudes

11. Wharton Applied Research Center , 1981

12. More individuals followed the recommendations of presenters who used OHP than those who did not
Presenters who used OHP were perceived as better prepared , more professional , more persuasive , more credible and more interesting
Groups that used OHP more likely to reach consensus on their decisions

13. Cabeceiras , 1972
10. Organisation & discussion

14. Teachers who use the OHP tend to be more organised
Students participated more frequently in discussion

15. LIMITATIONS

16. 1. Not preprogrammed effectiveness depends on the presenter
cannot display visual sequence or audio

17. 2. Not self-instructional
Designed for large-group presentation
Not suitable to independent study
Captions & audio tracks would not be self-instructional

18. 3. Production process required
Printed materials & nontransparent items cannot be projected immediately
Have to transfer into transparencies first
Example : magazine illustrations

19. 4. Keystone effect
Misrepresentation of images is more common than other projection systems
Discrepancy in levels causes a distortion referred to as the ‘keystone effect’
projector commonly placed at desktop level to facilitate the instructor’s writing on transparencies
the screen needs to be placed on a higher level for unobstructed audience sightlines