Tutorial 16: giving good talks, part 2: the slides
September 27, 2011
Preparing a talk is a time-consuming process, and there’s no question that getting the slides ready is where the bulk of that time goes. But unless you understand exactly what it is that you’re going to talk about, even the best slides won’t rescue your talk from mediocrity, so before you fire up PowerPoint, go and read part 1 of this tutorial, on finding the narrative. Seriously. The slides are how you convey your message, and they’re important. But not as important as what your message is.
Assuming you know what story you’re trying to tell, here is the overriding principle of slide design: make yourself understood. Remember again that you have something less than twenty minutes in which to make your rich, complex research project understood to a hall full of strangers who have just sat through five or ten or fifteen other presentations. They will be mentally tired. Help them out. Make every slide tell a clear story.
The slides for a conference talk are science, not art. That doesn’t mean they have to be ugly — of course it doesn’t. But it does mean that whenever you find yourself facing a choice between clarity and beauty, go with clarity.
That means you do not want your slides to look like this:
OK, that is not even beautiful. But it does illustrate some horrible mistakes, and we’ll touch on all of them in what follows. For now, just remember that the purpose of a Results slide is to help the audience know what your results were.
So how do you make yourself understood?
1. Use the full size of the screen
Most importantly, don’t “frame” your content. You have a specific amount of space in which to present your work. Don’t throw any of it away. Although the super-bad slide above may look extreme, I have seen plenty to slides that present, say, specimen photos in about the same amount of space as the graph above occupies. So, then:
- No picturesque borders.
- We don’t need the talk title, or your name or address on every slide. You can tell us once at the start of the talk and then, if you like, once more at the end. If we truly forget who you are in the middle, we can always look at the programme. If we forget what you’re talking about, then your talk has more profound problems.
- That goes double for logos. We do not need to see the following more than once (or indeed once):
- Your institution’s crest
- The conference logo
- Logos of funding bodies
We don’t need any of that stuff, and all of it wastes precious real-estate. Space that you could be using to tell your story.
Most important of all: use as much space as you can for your images. Specimen photographs, interpretive drawings, reproduced figures from the literature, graphs, cladograms, strat sections — whatever you’re showing us, let us see it.
In my own talks, I like to make the picture fill the whole slide. You can usually find a light area to put a dark text on, or vice versa. I often find it’s useful to give the text a drop-shadow, so that it stands out against both light and dark background. (You can find that option in Format -> Character… -> Font Effects if you use OpenOffice, and no doubt somewhere similar in PowerPoint.)
If the aspect ratio of an image that I want to use is not the 4:3 that projectors give you, then I will often crop it down to that aspect ratio, if some of the edges of the image are dispensable, so that the cropped version is properly shaped to fill the screen.
(On image resolution: most projectors seem to be 1024 x 768, maybe some these days are 1280 x 960. There’s no point using images at a higher resolution than that: your audience won’t see the additional information.)
Hopefully you won’t need too many words on your slides, since you’ll be talking to us about what we can see. But what words you use, we need to see. Specifically, this means:
- Use big fonts. There is absolutely no point in showing us an eighty-taxon phylogenetic tree: we just won’t be able to read the taxon names. I tend to make my fonts really big — 32-point and up, which actually is probably bigger than you really need. But you don’t want to be smaller than 20-point at the absolute minimum.
- Use high contrast between the text and background. That usually means black on white, or (if you must) white on black. Well, OK — it doesn’t literally have to be black, but it needs to be a very dark colour (I often use very dark blue). And it doesn’t literally have to be white, but it needs to be a very light colour. (I occasionally use a very pale yellow “parchment”-type colour, but less often.) Do not use grey text or a grey background. Especially do not use grey text on a grey background, even if they are fairly different greys and the muted effect looks classy. You’re not shooting for “classy”, you’re shooting for “legible”. Because you remember the prime directive that you’re trying to make yourself understood.
- If for some reason you must use a non-black, non-white text or background, don’t make it a highly saturated colour. Some combinations, such as a red on blue, and virtually impossible to read.
- No vertical writing (with the possible exception of short y-axis labels on graphs). If your cladogram’s taxon names are vertical, turn your cladogram around. Redraw it if necessary. If the audience have their heads on one side, you’re doing it wrong.
3. Font Choice
Apart from size, what else matters about fonts?
- Avoid elaborate fonts, such as the URW Chancery L Medium Italic that I used for my name and affiliation in the Bad Slide at the top. They’re hard to read, and at best they draw attention away from the message to the medium.
- Pick a single font and stick with it for consistency. Or if you wish, one serifed font (for body text) and one sans-serif (for headings). But you should have little enough text on your slides that it’s practically all headings.
- Stick to standard fonts which you know will be on the computer that will be displaying your presentation. In practice, the safest approach is it stick to Microsoft’s “core fonts for the web” — which is plenty enough choice.
- You might want to avoid Arial, which is widely considered particularly ugly. Other ubiquitous sans-serif fonts include Trebuchet and Verdana, which are both rather nicer than Arial (though Verdana’s glyphs are too widely spaced to my eye).
- Do not use MS Comic Sans Serif, or no-one will take anything you say seriously. I don’t just mean your talk, I mean ever, for the rest of your life.
Why is it important to stick to standard fonts? Because of size, spacing and positioning. Your computer may have the super-beautiful Font Of Awesomeness and it might make your slides look beautiful; but when you run your PowerPoint file on the conference computer, it won’t have Font Of Awesomeness, so it will substitute whatever it thinks is closest — Arial or Times or something. Not only will you not get the visual effect you wanted, but the glyphs will be different sizes, so that your text will run off the edge of the page, or fall right off the bottom.
(Handy household hint for users of Debian GNU/Linux and variants such as Ubuntu. Make sure that you have the MS core fonts installed on your computer, so that OpenOffice can properly display your slides as you’re designing them, rather than substituting. sudo apt-get install ttf-mscorefonts-installer, restart OpenOffice, and you’re good to go.)
4. How many slides?
I need to mention this issue, if only to say that there’s no right answer. I don’t say that lightly: for most slide-design issues, there is a right answer. (Example: should you use MS Comic Sans Serif? Answer: no.) But number of slides has to vary between people to fit in with presentation styles.
I tend to use a large number of slides and whiz through them very quickly — my SVPCA 2011 talk had 80 slides, and in 2010 I had 92 slides. Lots of them are parenthetical, sometimes just a silly joke to make in passing a point that I am already making. If you miss such a slide, it doesn’t really matter: it’s just light relief and reinforcement, not an integral part of the narrative.
But that many-slides-slipping-quickly-past style doesn’t suit everybody. In the eighteen minutes or so that you get to give a talk (allowing a minute for messing about getting set up and a minute for questions), getting through 80 slides in those 1080 seconds gives you an average of 13.5 seconds per slide.
Lots of people prefer to use fewer slides and talk about them for longer. You can give an excellent talk with very few slides if that approach comes naturally to you: step slowly through nine slides, talk about each one for two minutes.
Once you’ve given a few talks you’ll know which approach works best for you, and you can design accordingly. For your first talk, you’re probably best off aiming initially somewhere in the middle — thirty or so slides — and then seeing what happens when you dry-run the talk. (We’ll discuss that next time around.)
I’ve touched on this one already, but it’s best to use as little text as possible. That’s because you want your audience listening to your story, not reading your slides. I used to put a lot of text in my slides, because I wanted the PowerPoint file to stand alone as a sort of a record of the talk. But I don’t do that now, because a talk involves talking (clue’s in the question). I include enough text to remind myself what I want to say about each slide (sometimes just one or two words; often none at all). And I try to make sure there’s enough to let the audience know what they’re looking at if I zoom straight past it. For example:
I used this slide to briefly tell a typical taphonomic story of a sauropod neck. But I didn’t need to say that I was using diagrams of the neck of Sauroposeidon taken from Wedel et al. 2000, so I just shoved that information on the slide for anyone who was interested. That way I didn’t have to break the flow of my narrative to impart this information.
Use a consistent colour palette. If you’ve used dark blue text on white for half of your slides, don’t switch to black on pale yellow for the other half. It’s not a hugely important point, but it all contributes to helping the talk go down smoothly. You’re getting rid of mental speed-bumps that could stop your audience from giving their full attention to the story you’re telling.
Where possible, avoid putting important information at the bottom — in, say, the lower 10-15% of the slide. That’s because the lower part of the screen can sometimes be obscured by the heads of the people in the front rows.
Avoid hatching, which can look terrible on a screen, in a way that’s very hard to predict. In the Sauroposeidon taphonomy slide above, for example, the lost bones are “greyed out” using a flat grey colour rather the close diagonal lines of the original. I knew it would look right on the screen.
Skip the fancy slide transitions, animated flying arrows, and suchlike. It’s just distracting nonsense that no one in the audience (or anywhere else, for that matter) needs to be exposed to. It’s just gross. Also, as with fonts, you may end up giving your talk from a machine with an older version of PowerPoint that doesn’t support the turning of animated pages and the bouncing arrival of arrows and clipart, and then your presentation will either look stupid or fail to run entirely.
You might want to draw highlighting marks on your slides, e.g. circles around the relevant parts of a specimen photos. That will save you having to mess about with the laser pointer later. (I will have much to say about the laser pointer in part 4). I like to show two consecutive slides: one of the unadorned photo, then one that’s identical apart from the addition of the highlight, like this:
Then as I am talking about the first slide, “in order to mount the vertebrae in something approaching a straight line, they had to leave a huge gap between consecutive centra”, I’ll step on to the next one, which highlights what I’m saying. Slick, no? (This is part of why I end up with such high slide counts.)
A pet hate: don’t write “monophyletic clade”. If it’s a clade, it’s monophyletic by definition. “Monophyletic clade” is like “round circle”, “square square” or “boring ornithopod”.
And finally …
Show us specimens. We are vertebrate palaeontologists, and we love vertebrate fossils. No-one goes into the field because of a deep and abiding passion for graphs or for tables of numbers. We understand that from time to time you’ll need to show us those things in order to tell the story, but nothing makes an audience happier than big, clean photos of beautiful specimens.
Well, that’s it — how to make good slides. Next time we’ll look at rehearsing the talk. (It’ll be a much shorter post than this one.)