Assertion–evidence slides

Most slides have a short topic title ("Results") and a list of bullet points. Michael Alley and colleagues at Penn State proposed a better design: assertion–evidence.

The design

• Headline: a full-sentence assertion, the one thing this slide shows. "Colour augmentation helps most when data is scarce."
• Body: visual evidence for it: a graph, photo, diagram or short equation. No bullet lists.
• You supply the explanation by speaking.

Does it work?

In a 2013 study by Garner and Alley, engineering students who saw assertion–evidence slides understood and remembered the content better than those who saw traditional bullet-point slides. It also fits Richard Mayer's research on multimedia learning: people learn better from a picture plus speech than from a picture, speech and the same words written on screen, because reading and listening compete.

A famous warning

After the Space Shuttle Columbia disaster in 2003, the accident investigation board criticised a NASA PowerPoint slide where a crucial warning was buried in a low-level bullet point. Edward Tufte later used it to show how bullet hierarchies can hide what matters.

How to convert a slide

1. Ask: what's the one point of this slide?
2. Write it as a sentence in the headline (two lines at most).
3. Replace the bullets with the image that proves it.
4. Move any extra text into your speaker notes.

RememberHeadline: the claim, as a sentence. Body: the visual evidence. You: the explanation.