At least 80% of scientific talks are bad. Most of these could be vastly improved by improving the slides. It may take a little extra time up front, but whose time is more precious? Yours, or the total of all the people in the audience?
Within my suggestions below, a common theme emerges: Simplify!
Fewer complex figures
Many would agree that including too many equations is bad practice, with the rationale being that the audience cannot follow along quickly enough. People seem to not realise that the same is true for figures. Slides are typically only up on the screen for one minute. Even with the speaker describing the results, a complex figure can induce cognitive overload.
Complex figures include those with multiple panels, abstract quantities, or many variables on the same panel. These are appropriate for a journal article, not a presentation. Simplify these slides in some way: show only a representative sample, show different panels on consecutive slides, or show smoothed output instead of raw data.
Build up figures piece by piece
Presenting complex figures might be unavoidable. In this case, build up the final graph one step at a time. Add a line to the graph, talk about it, then add the next and repeat. This is much better than trying to point the laser at a line, or saying things like “the blue line in the left plot suggests…”.
Creating slides that build up piece-by-piece will take extra time. But the final result is much easier for the audience to follow.
Fewer words per slide
Science is at its best when information is distilled into schematics, graphs, or conceptual models. Not long lines of text.
A google search for “words per slide” returns countless different opinions. Many suggest rules of thumb such as “no more than six bullet points” or “five bullet points of four words”. I think the goal should be zero (not counting titles and labels). If a text-heavy slide comes on the screen, I am never sure whether to attempt to read the slide or listen to the speaker. So when creating your slides, think to yourself why you are adding text. If it is simply a reminder of what you are meant to say, then get rid of it and spend some time practising your presentation.
Limit your conclusions
People wont remember any of your conclusions if you end with a slide with five long-winded conclusions. Stick to three at most and keep them brief. Here are the conclusions from a recent talk of mine:
Here is how it might have looked had I not kept it brief.
Use a white background
Photos, solid colors, or gimmicky templates as a background serve no purpose; using anything but a white background is unnecessary. The problem with these non-white backgrounds arises when graphs or other images are placed overtop. For example:
Simple is better:
Keep the slides neat and tidy
A hastily created PowerPoint presentation can quickly evolve into a kids scrapbook.