Slides are free

When I was in school, every classroom used to have a bulky metal box that lived on a wheely cart. The overhead projector.

It was a whole thing. We’d turn off the lights, the teachers would break out a folder full of “transparencies,” and we’d get ready to take notes. The powerful lightbulbs inside were expensive. The plastic pages and slides were expensive. Every slide, every square inch, was precious.

But today, slides are free. Just tap a tiny little button in the top left of Keynote or Google Slides, and you can have as many as your heart desires.

So why do so many of us keep acting as if they are a scarce commodity? Why do we try to cram every bullet, graph, and table onto one slide?

Maybe it’s a mistaken belief that fewer slides mean a simpler and easier-to-understand presentation. We’ve heard (and often experienced) horror stories of torturously long 100+ slide reports. Those are miserable – so maybe if I make sure I only use 10 or 20 slides, then I’ll be better off?

But that’s the wrong metric. We shouldn’t minimize slides – we should minimize friction! It’s higher friction to have 200 words of microscopic type on one slide than it is to have 10 separate slides of more modest scope.

In a 2011 study, researchers Sabra Brock and Yogini Joglekar examined the effectiveness of slides in the classroom. Across multiple environments, they found that the number of slides had no impact on outcomes – but that lower-density slides resulted in more effective lessons. More here:

The instructor with the highest teaching effectiveness comments and the one with the most negative both used a relatively high number of slides (35) per session. However, the higher rated instructor used only an average of 3 bullets and 20 words per slide, whereas the lower rated instructors used 5-7 bullets and 25-70 words per slide.

My own students are about to present their midterm projects next week, and I was reminded of the team a couple of years back that presented their entire marketing pitch on one slide. They got up in front of the class and loaded a title slide, the one mega slide, and then a thank you slide. They didn’t win the assignment.

Most presentation decks are too short, not too long. Slides are free.