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.)

2. Legibility

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.)

5. Miscellaneous

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.)

20 Responses to “Tutorial 16: giving good talks, part 2: the slides”

  1. Really great series. A good rule of thumb I try to stick to is 1 minute/slide on average, but then as an experienced speaker I violate that rule a lot (closer to 2-3 slides/min) and just try to get my students to do it. :) I think a faster rate can annoy the audience.

    But most importantly perhaps, target your slides to the audience. Very important in this increasingly interdisciplinary age. Minimize jargon when you can (and abbreviations). If you’re speaking about biomechanics in a paleo audience, don’t assume that everyone is very familiar with what a moment is, or that walking tends to be abstracted mechanically as an inverted pendulum. If presenting a phylogeny slide(s) to engineers, be sure to explain how to read a cladogram, in brief. In short, put yourself in your average audience member’s shoes and ask, “What am I not going to understand about this slide?” and fix that.

  2. Mike Taylor Says:

    Thanks, John, excellent points. (I am sure you will have plenty more to say about Part 4, delivery! :-))

  3. Stu Pond Says:

    From a design point of view, it can be an idea to set up a grid which you can then use to ensure visual continuity across the presentation. In stinkin’ Powerpoint I believe you can set up a template and it can be an idea to set up one for images, one for bulleted lists etc. Use the same font for headings, captions, body text etc. It’s best not to use black as a background as it doesn’t project (obviously) and the projection surface becomes your slide background.

    Don’t forget you can embed wmv’s and mpeg 1’s too so you can add footage and animation to a presentation.

  4. Mike Taylor Says:

    Well, Stu, it looks like I am doing to disagree with all three of your points :-)

    First, I would never use a grid because that’s letting the form dictate the content, and I want to do the opposite. If my content was of a form that would fit onto a set of templates, I’d know I’d muffed the story construction. There’s a reason Buffy the Vampire Slayer scenes aren’t laid onto a set of templates, and that reason — primacy of narrative and engagement — is just a valid in a conference talk.

    Second, black is a good background colour because it doesn’t project. It doesn’t impose a spurious additional set of borders on your content — the border of the screen is all you need, and you can go right up to the edge of the slides without it looking cramped. The only reason I usually favour a white background is that figures in journals are almost invariably black-on-white, and when I use them in a slide I like to have them sit comfortably on the background.

    Finally: I have indeed seen videos embedded in conference talks to good effect, but I’d be wary about attempting it myself because I’ve seen it go wrong too many times. In a few years it will be safer, but for now my advice would be to include video only if your story actually needs it, rather than just because it’s a cool addition.

  5. Andy Farke Says:

    A truly excellent post! My only addition would be to use the whole slide, but be aware that you may not get the whole slide when it’s projected. I usually plan on 5-10% “waste” on the edges, because inevitably the screen isn’t quite big enough for the projected image, or something is misaligned, or whatever. So, full-screen photos are excellent, but never put anything you care about on the margins (I’ve seen this happen more than once).

  6. Andy Farke Says:

    (above comment would of course be a corollary of your comment about the bottom of the screen)

  7. Dave Godfrey Says:

    Unaccustomed as I am to public speaking, I’m inclined to agree with using a template- if only because as noted it gives visual continuity across the presentation- if you’re not going to switch colours, why move positions of titles, graphs, etc, unnecessarily unless the content forces you to do so?

    I definitely agree that using video files is a really bad idea- I don’t think I’ve seen it work first time whenever its been used.

  8. Stu Pond Says:

    I thought your slides were excellent Mike as they are not text heavy. As you say, too much text eventually becomes overwhelming but you’d be surprised how many clients can’t help piling their presentations with copy that only serves to confuse the viewer (I’m going to write a thesis on the effect of Powerpoint on the internal visualisation capacities of project managers, clients and writers when it comes to animation and the presentation of text on a screen. Believe me, that damned programme is changing the way people actually envisage some types of animation).

    On the subject of grids, a grid system helps organise the content and provide consistency across a presentation; it’s a way of letting the information speak without the distraction of an unstructured screen, providing clarity for the transmission of information. It allows the presenter to set up a visual environment that will allow the viewer to see the information quickly and easily, these visual references establish themselves over the first few screens of a presentation and aids the viewer in navigating around the information presented. If it’s not structured, presentations run the risk of looking cobbled together. At the very least, if there’s no grid to constrain the various elements only use one image per screen.

    In my experience of scientific presentations (working alongside PP bods rather than actually authoring the presentations, of which I’ve only created a couple for myself) the use of templates for visual consistency also eases the production process itself by providing a structure to carry the content which can be populated quickly and effectively (people actually talk like this in my business).

    The colour choice is subjective, but professional slide pack creators rarely use black backgrounds, especially for text slides. They do tend to stick to dark backgrounds with light text as you suggest. I have used subtle, treated backgrounds in the past but projector quality is highly variable and this can be a waste of time. I have created many branded slide backgrounds that have used some quite strident colour screens, although I agree these might be a distraction for a palaeontology presentation.

    Of course, if you are delivering on a venue’s computer then including movies can be a real issue as the pres will be untested before you present, however if it’s you’re own kit then you’ll know the limitations. In my own job many of the motion graphics and animation pieces I create for various symposia are delivered as wmvs and played through Powerpoint instead of dedicated laptops as they used to be.

    At the end of the day though, content is king, and a brilliant article Mike.

    BTW, if you’re an Apple or iPad user it’s worth checking out Keynote, which is far superior to the dreaded Powerpoint and offers a range of quite useful, er, templates that actually look presentable.

  9. Jon Tennant Says:

    Boring ornithopod?! Rude..

    Excellent advice though. I’ll be sure to repost this to my MSc class, even if they all hate dinosaurs (lack of interest in dinos is significantly correlated with boringness of talks).


  10. Andy Farke Says:

    One other thing to add: I’ve begun to see the creeping menace of Prezi in some presentations (not yet at a scientific meeting). Don’t use this program. Ever. At best, it’s too “cute”, and at worst it (literally) induces nausea.

  11. Andy Farke Says:

    And yet another (hmm, maybe I just just write my own blog post on this): OpenOffice.org Impress users who have to present their files from PowerPoint should always open the files on an installation PowerPoint before the talk. 99% of things work OK, but there are inevitably little annoying quirks that show up, in terms of slightly different spacing, different treatment of colors, etc. I ended up doing a last minute edit of my talk at the hadro symposium last week, for this very reason. . .I wanted to use strike-through on some text, but for whatever reason PowerPoint refused to display it!

  12. Neil Says:

    Probably descending into unnecessary common sense minutiae here, but I have been burned enough times that it warrants a mention:

    Mac PP users (and probably Windows users too) should always “insert” images from the menu rather than dragging and dropping to avoid the dreaded “Quicktime TIFF-Decompressor” error that has caused endless grief. This seems to have been fixed on newer versions of PP (a poor student, I’m still using Office 04).

    Of course, to generalize from Andy’s comment above, it’s always a very good idea to check your presentation carefully whenever presenting on a machine other than the one you created the presentation on, this goes doubly if you are switching platforms, software, or even different versions of the same software. Likewise it’s highly advisable to check your presentation on a projector before the meeting, sometimes text and figures that appear absolutely solid on a monitor are washed out or illegible on a screen.

    Finally, when slide-FAIL does occur (and it will) don’t get flustered! I can’t count the number of talks I have seen that totally loose their steam when the presenter get’s bogged down: “and here you can clearly see the linear relationship between scrotal size and annual income … oh, or, well that’s what you *should* be seeing, looks like … um, where is it !? Gosh, I think … well … OK. Let’s just skip that and move on … uh.” I have been the victim/perpetrator of this myself a few times. Remember the visual aids are supposed to augment your verbal presentation, not vice versa. If you can plough through the corrupted slide with minimal fuss, you’ll be dealing with a few momentarily raised eyebrows and cocked heads rather than being totally written off by the audience for the next ten minutes.

  13. Neil Says:

    Oh and, er, always proofread your text or, better yet have someone else do it. Fresh eyes can make a big difference.

    Minor typos like “loose” when you mean “lose” or “get’s” when you mean “gets” can distract your audience and undermine your credibility when projected at ginormous proportions.

  14. David L G Rice Says:

    “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.”

    \As the spouse of an art historian: The trouble isn’t that your visually cluttered colleagues are too interested in art and beauty. Rather, they are insufficiently educated in visual and aesthetic strategies. To put it in lolcat terms, THEY R DOIN IT RONG. Your post is a good corrective to that problem.

  15. JCK Says:

    I’ve found that a good solution for the font / versioning / etc problem is to export to pdf and then use acroread or some other pdf viewer to view the slides.

  16. […] o segundo post é de um blog que de vez em quando eu cito, o de paleontologia… neste caso, é mais um da […]

  17. […] we posted the first two articles in a series of four on giving good talks: part 1 on planning, and part 2 on preparing the actual slides.  Then we got distracted and posted a whole sequence of articles on Open Access ([1], [2], [3], […]

  18. […] figured out a clear, compelling story that you want to tell from your research; you should have clear slides with striking, relevant images and no visual distractions; and you should have rehearsed your talk […]

  19. […] Next time: the slides. Share this:FacebookRedditTwitterLike this:LikeBe the first to like this. Posted by Mike Taylor Filed in opportunities, Science communication, stinkin' mammals, Tutorial 6 Comments » […]

  20. […] turns out that G. K. Chesterton conveniently summarised all of my advice on slide preparation more than a century […]

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