Using Overhead Projectors

Media Services
Robert A. L. Mortvedt Library

• Face to face contact with audience
  • Eye contact possible
  • Can pick up verbal and nonverbal cues to understanding
• Projector located in front of room and near speaker for easy access
• Can be used to focus audience's attention
  • On to focus attention on visual material
  • Off to focus attention on speaker
• Effective in a fully-lighted room; audience can follow handouts or take notes
• Ability to modify transparencies during presentations
  • Highlighting important points with transparency pen
  • Writing on blank acetate film like a chalk board
• Sequence of material can be modified during presentation
  • Accommodates audience questions or interest
  • Can abbreviate or extend sections of presentation
• Unframed transparencies easy to store and transport; easily fit in file folder
• Overlays can be used to simplify complex information into layers
• Short lead time (minutes) for preparation of transparencies
• Low cost of transparency material
  • $.30 per sheet for one color

• Continuous tone color transparencies are costly
  • $1.50 per sheet for continuous tone color output from DeskWriter printer
• Overhead projector is bulky and heavy to transport
• Framed transparencies are bulky and difficult to store
• Pages from books cannot be used effectively without modification since text will usually be too small for audience to read.
• Overhead projection is perceived as being "less professional" than slides in a formal setting.

• Use ON - OFF switch to focus attention
  • ON to focus attention on visual
  • OFF to focus attention on speaker

  Turn the projector off when you're not using it for extended periods of time to reduce distraction for audience.

• "Chalkboarding"
  • Use projector stage like a chalkboard
    • Acetate sheet or roll
    • Water soluble transparency pen
  • Notes for presentation can be:
    • Projected with presentation
    • Added in conjunction with presentation
    • Revealed one point at a time (see progressive disclosure)
  • Points in group discussions can be:
    • Listed to verify communication
    • Used to focus further discussion
  • Charts, grids, illustrations can be:
    • Prepared in skeleton form prior to presentation
    • Modified, filled in labeled, etc. during presentation
• Pointing for emphasis
  • Concentrate attention on message being covered
  • Use opaque shapes like pens, coins, arrows, etc.
• Highlighting
  • Use pen of different color from original. (Be sure to use water-soluble pen if you need to re-use the original transparency.)
  • Use underline, circle, arrow, check, bullet, star, etc. as emphasis codes for your audience
• Progressive disclosure with opaque cover
  • Reveal topics one point at a time
  • Direct attention to point being covered
  • Prevent distraction
• Overlays
  • Simplify complex concepts
  • One part of complex whole can be presented at a time
  • Parts can be joined for discussion of whole

Below are a few essential items that may make the difference between a successful and unsuccessful presentation using overhead projection. Some of these are especially important if you will be presenting in a room without access to audio-visual support services.

• Extension Cord - Rooms sometimes have the power outlets located in the most inconvenient locations. An extension cord may resolve such difficulties.
• Ungrounded Plug Adapter - Some buildings still do not have three-prong grounded outlets. A two-prong adapter will allow you to use these older power outlets without damaging the overhead projector plug.
• Spare Bulb - Most of the PLU overhead projectors have spare lamp changers inside the projector. But a spare bulb is always good insurance. Make sure you know how to change the bulb in case it burns out during your presentation. Do not touch the glass surface of bulbs with your fingers, but handle bulbs by their metal or porcelain bases or with a handkerchief.
• Transparency Pen - You may want to write on a transparency to illustrate, clarify, or highlight a point. If you plan to use a transparency over again, be sure to use a water-soluble transparency pen. You may want to cover transparencies with clear sleeves to avoid damaging your original.
• Acetate Film - Extra blank acetate film provides additional "chalkboard space" for responding to audience questions and comments.

Maintained by: Layne Nordgren (nordgrle@plu.edu)
Last Update: 09/13/97