Two years ago I blogged on the importance of presentation idiom, and on the two main presentation idioms, Ballroom style and Conference room style. I think the difference between the two styles is critically important and not well understood, so I am repeating that post here, with some minor edits.
Each presentation situation calls for a particular presentation idiom—a form of expression and a set of design principles. Contrary to the popular complaint, the problem with PowerPoint™ is not that it forces you to design a presentation in a particular way. On the contrary, it doesn’t. And that's the problem: PowerPoint allows you to mix design elements from different idioms, which, I believe, accounts for much of the ugliness and ineffectiveness of most presentations.
There are two fundamental presentation idioms, which I call Ballroom style and Conference Room style. The Ballroom style presentation is what most typical PowerPoint presentations are trying to be: colorful, vibrant, attention-grabbing, and (sometimes) noisy. They typically take place in a large, dark room such as a hotel ballroom.
The Conference Room style presentation is much more understated: less use of color, more details on each page, printed rather than projected, and more suited to your average corporate meeting or conference room.
Ballroom style presentations should be used when the objective is to inform, impress and/or entertain the audience. The information flow in a Ballroom style presentation is primarily one-way, from presenter to audience. This style is appropriate for audience sizes from a few dozen people to several thousand.
The look that you are trying to achieve with Ballroom style is that of the evening news: visually rich and thoroughly professional. To do this, you will want to project your presentation rather than hand it out, so that you can make extensive (but always appropriate) use of color, animation, and sound. (Color, animation or sound is appropriate when it is used to convey or emphasize information; it is inappropriate and should be ruthlessly eliminated when it serves only to embellish or distract). The length of a Ballroom style presentation should be approximately 1 slide per minute of presentation.
Conference Room presentations are more suited to meetings where the objective is to engage and persuade your audience and change their behavior. Information flow in this idiom is expected to be two-way, and this style is therefore more suited to meetings with smaller numbers of people, say two to 25. They can be used with larger audiences, though: I have used this idiom to support an interactive conversation with as many as 80 people in an amphitheatre-style classroom, or 200 people on a teleconference.
A conference room presentation should look more like an architectural drawing than something you’d see on television, and it is best delivered on paper. Paper has the advantage of allowing much greater resolution and therefore more information on each page; you can use font sizes as small as 9 point without difficulty, whereas in Ballroom style 24-point is usually the minimum safe size. More information on each page also facilitates more productive conversations, because it helps avoid the “turn back 2 slides – no, 3, what was that point there?”-type of confusion since all the information for the discussion of the moment is right in front of everyone on a single page. Paper delivery also allows people to write on the presentation, so that they can engage with your content better and communicate back to you any suggested changes. Also—as Edward Tufte notes—it sends a message that you are confident in your content, because you are allowing your audience to walk away with it. Because Conference room style presentations contain so much more detail on each page, they tend to have significantly less pages – from about 12 to as few as 1 page per hour of meeting time.
Mixing idioms – like mixing metaphors – is a recipe for confusion and deficient communication. Understanding when to use Ballroom style and when to use Conference room style, recognizing which elements are proper to each idiom, and never confounding the two, will lead to clearer, more attractive, and more effective presentations.