One of the cardinal rules of slide design is: one slide = one topic. Yet even applying that rule, many people still cram their presentation visuals so full of material that the purpose is unclear. So here’s another rule to apply: every slide has to have a point that the audience can absorb in seconds.

Presentation pro and author Nancy Duarte says slides are a glance media, much like billboards. Brain researcher John Medina says multitasking is a myth. People can’t listen to a presenter and read slides at the same time. Other research states that people lose interest in slides very quickly, no matter how well designed they are. The evidence is overwhelming: you need to make your point crystal clear and do it fast.

So, when you’re drafting your slides, give them a once-over asking: what’s the point? Is it clear? Will my audience get it in seconds? If not, it’s time to do more work to bring key ideas into focus. Here are three things you can do to sharpen your slides.

• Create a headline that states the point in words - Make it a complete thought, rather than a complete sentence, to keep it short

• Highlight what you want people to focus on — Use bolder lines to draw the part of a graphic you want to discuss, or use a brighter colour to emphasize important bars in a chart.

• Use builds to layer information on the slide as you talk about it — That way people don’t have to figure out what’s important about a mass of text or complex graphic all at once.