Slides are a double-edged sword: They can effectively dramatize a difficult concept, but they also turn the audience's attention away from you, and your visual self is your most effective weapon as a speaker. So if you're going to use slides, they have to be very good for two reasons: to make up for the fact that you're plunging yourself and your audience into darkness, and to counter the tendency of most people to lose interest when they hear they're going to see slides. I have seen members of an audience deflate when they hear that slides are part of the presentation, and it's up to you to prove to them—very quickly—that what's coming up won't be disappointing.
Your voice has to be especially lively and dynamic if your presentation takes place in total darkness after a meal. Try to leave some light on; what you lose in slide clarity you more than gain back in audience involvement and alertness.
Despite the drawbacks, slides can work very well and are good visual aids for large audiences. Some situations really call for their use; for example, a surgeon demonstrating a new surgical technique, an engineer showing the ground around a new facility, and a real estate dealer presenting a property would all welcome the ability of slides to present in an instant what would take many words to convey. Sophisticated computer-generated graphics are common in both slide and overhead projector presentations and help speakers convey complicated concepts elegantly.
Slides also give repeat speakers flexibility; they can update their presentation by adding or subtracting slides without changing the entire display.
In fact, fewer and fewer people are using slides today—but they are still prevalent in some industries. If you have a good application for slides and are not using them to print words that you are already saying, the following rules of thumb will help you produce effective ones:
Target what you want the audience to remember, and build your slides around these points.
Use only as many slides as you really need. Don't waste the audience's attention by inundating it with superfluous slides.
Practice your slide presentation. If you show a slide, make sure you refer to it; don't show a complex slide and continue talking without explaining it. Otherwise, your audience will be trying to figure it out while you're talking about something else.
Don't leave a slide on the screen longer than you have to. When you're through talking about it or explaining it, go on to the next one.
Prepare the technical aspects carefully. Make sure ahead of time that your slides are in the correct sequence with the right side up. Number them clearly and make sure your projector and slide carousel are in good condition. Double check everything before you begin: Are the electrical outlets in the right places? Do you have extension cords if you need them?
Establish good communication with your listeners before you begin the slide show. Let them know you're the expert, not the slides, and that you really want to be there. Many audiences have sat through boring slide presentations, and you must counterbalance that experience. Show them you are a good presenter who uses slides because you want to, not because you have to.
Look for places within the presentation to turn the lights back on. Some presenters feel that you should turn the lights off only once, that flicking them on and off is very disorienting for the audience. I disagree. I think that turning the lights back on can serve as a pick-me-up for the audience, and keep their attention moving forward.
Don't start your "slide show" without talking to the audience—with the lights on—for at least two minutes.
Because you don't want to put the slide up before orienting the audience to it, you may need a default slide, one that goes up while you are making a transition. For example, in my presentation, I might put up a slide that says, "NEVER BE BORING." If your presentation was about change, your "transition" slide could read: CHANGE = GROWTH AND PROSPERITY. A company like Nike, with the recognizable slogan, "Just Do It," might use this slide as their default so that people see it many times. You can add to the effectiveness and impact of your message by using the default strategy.
Be careful when using slides to give the audience a break. Some presenters like to use cartoons when going through a transition, just to break things up a bit. However, unless the cartoon is directly related to your topic, it can be distracting and make it difficult for the audience to get back on track. Used well, however, "break" slides can be very effective. I once attended a presentation on osteoporosis, where, during transitions, the speaker showed photos of a woman from age 50 to age 80, and how she changed. Another speaker, a financial planner trying to convince her audience to keep up with inflation, used break slides showing what S 100 bought in 1940, 1955, 1980, 2002, etc.
If something goes wrong with the slides—if you drop the carousel, or they are out of order, or the switches fail, or there is some other emergency—take a five-minute break to fix it; don't try to muddle through the problem. Before you speak, plan in your mind what you will do if you suddenly can't use your slides.