I remember in grad school, for presentation assignments, teachers will require a set number of slides as an element of the grade. Many people with that experience often complain about high slide counts in presentations. How many slides are too many? How does one go about deciding the number of slides to include in a presentation? Are there rules which will make this decision an easy one?
Unfortunately, there are no generally accepted rules when it comes to the number of slides in a presentation. The best answer is “it depends.” It depends on the duration of the presentation, the degree of details you wish to share, and your familiarity with the guidelines of powerful presentations.
Slide count owns some of the blame for people’s tendency to cram too much information into one slide. Too much information on a single slide forces the presenter to use the slides as a crutch. Moreover, the brain activity required to digest all the points on a slide proves overwhelming for both the presenter and the audience. As a result, some presenters carry paper notes; others simply read the slides. The audience, invariably, just falls asleep during the presentation.
Paper notes, while not a big problem, distracts the presenter and produces avoidable noise. The presenter’s distraction becomes a source of distraction for the audience. Ultimately, the message suffers. Worse case scenario, many audience members forget the important message, only remembering the distractions. Reading the slides produces similar results. When the presenter reads the slides, he has to turn away from the audience. In either case, the audience is left wanting because the crucial element that connects it to the presenter is no longer available.
In addition to these issues, high information density on a slide means that the audience has to work much harder to retain and recall the information. Presentation professionals refer to the work the audience has to do as cognitive load. A high cognitive load pushes the audience to stop trying. The audience should not have to work too hard to understand and retain the information.
What does this have to do with slide count? Everything. While the limitations – arbitrary as they may be – that educators place on us when we were in school make sense from the workload point of view, it encourages most of us to ignore why we are doing a presentation.
The final reason slide count shouldn’t matter is our dwindling attention span. Scientists argue based on research that the average attention span of people is down to between 15 to 30 seconds. If you wish to engage your audience, you have to keep the story moving with a new slide every minute. This excludes the possibility to stay on the same slide for five minutes. Not a good idea.
My points are well and good. But the question remains. How many slide is too many? The only rule of thumb that I can recommend is the following. If you find yourself changing slides several times every minute, more than likely, you have too many slides. A nifty trick is to perform a dry-run of the presentation to people you know. I found that these dry runs provide the best feedback. Before the big day, you will have had the time to recalibrate your message, decrease the number of slides if necessary. The most important item in your presentation is not the number of slides. It is the story you want to tell. It is the way you tell that story. And it is the capacity of your audience to remember the message long after you are gone. Don’t let slide count stand in the way of an amazing story.