Hello again, Blogosphere!
I spent last week in Toronto at the annual AIAA Guidance, Navigation, and Control Conference. This is a huuuuuuuuuuge conference of engineers from academia, military, and industry all presenting papers about their research. So, I got to see a lot of Powerpoint presentations. (Okay, okay, supernerds, there were some PDFs and Keynotes. But “Powerpoint” is pretty much like “Kleenex” these days.) And an awful lot of the presentation slides I saw looked something like this:
Fine, right? I mean, this is a technical venue, full of super-brainy engineers. We want the facts, ma’am, just the facts, in all their glorious mathematical detail, and style means nothing. Right?
The first rule anyone will ever tell you about giving any kind of presentation is to know your audience. And if I’m in the audience at a conference like this, then I’m spending a full day listening to technical talks and you have only twenty minutes to make me think that your research is as cool, interesting, or relevant as the title made it sound when I picked it out of the lineup that morning. Because I’m still holding the conference program in my hand, and I have a notepad and pen ready to jot down research ideas the last cool presentation made me think of, and I might have my laptop in my bag, so I’m not at a loss for things to do if you’re not very exciting. In other words, not only do you need to convey your technical material, but you also need to keep me interested and/or entertained, at least enough to keep me listening to your technical stuff.
It’s a tall order.
I’ve been told that I do a good presentation, though, so I’m going to share a bit of my philosophy for what a technical presentation should be like. Here are the points that I start from:
- Nobody wants to see lots of equations. Some are necessary, sure, and they can be a great way to add technical gravitas, but a 20-minute presentation is a much better time to show off results, pictures, movies, hypotheses, conclusions, possibilities, tricks, and excitement. And if the conference is like GNC, requiring a paper with each presentation, then all the equations go in there, anyways. The oral presentation is for highlights, not derivations.
- These presentations come in the middle of a solid block of otherwise identical presentations that are going to blur together in the audience’s minds. So, they need to be distinctive. In other words, a bit of flash and polish goes a long way. Also, attention-grabby things like pictures and movies are good, but not if they’re just thrown together in a clip-art sort of way. (There’s good attention to grab, and bad attention to grab!)
- Slides are visual aids. I mean both “visual” and “aids.” Think about both of those terms: slides are supposed to be for showing the audience things. And the slides in a live presentation are not supposed to be completely independent of the presenter: you should refer to them, but you are the one giving the presentation.
As an example of my own style, allow me to go through my recent GNC presentation slides and point out my thoughts on their layout, style, and content. If you want to follow along, most of the presentation itself is here on YouTube:
I think slides should be spartan. It’s not just that I’ve been lately trending towards minimalism in design – but it also bears thinking about exactly what information you think is important before you put it on a slide. The pictures, equations, and bullet points you select should be put on the slide to draw attention to them, and the slide should not include all sorts of accoutrements and fancy design stuff that distract from the actual content. I like to start all my slides from a “blank” template, and view them as an empty space which I can use to set off the things I want to talk about rather than trying to fill them with content. In general, I like to make slides that don’t include any extraneous information. (For example, everyone in the audience already knows what conference they are attending and what the date is. Not including the standard Powerpoint footer bar could buy you about 10% more slide space to work with.)
There are some things that technical audiences expect to see on each slide, and I’m willing to make some concessions here. For instance, many people expect some indications showing where this slide fits into the presentation, such as slide numbers. This serves two purposes: first, to give the audience a sense of how the “story” is progressing; and second, to give them something to refer to during the Q&A after a presentation. I also think it’s good to include some mark on each slide identifying yourself, such as a university logo or whatnot, because that helps drive home your technical “street cred.”
Finally, for years I have strongly favored dark backgrounds and light text or graphics. I do so for a simple reason: when projected against a wall in a dark room, light colors can look especially bright and sometimes seem to glow a little. Take an example with 100% black and white backgrounds and text, and with the same glow filter applied to the white parts. Clearly, the text in the top half of the image is not 100% black any more:
There are two ancillary bonus features for me in going to a white text/black background scheme. One is that I talk about space, and it helps to make my slides more space-y. Two is that not many people go for a black background, so it helps to make my presentations more distinctive, standing out in the audience’s minds. (Three presentations from my research group were the only ones I saw at GNC that had a black background.)
I think of the title slide as my opportunity to anchor my audience with my premise, and my last chance to catch someone wandering from session to session. So I want flashy stuff, and I want that stuff to connect with my title in such a way that it gives the audience some more insight into what my title keywords mean.
So, here, I have my paper title, authors, and affiliations, but I leave off the name of the conference, session title, date, or any other text. The title slide is not the place to make a point, and again, I presume my audience already knows where they are. My graphic, showing a modular spacecraft in various stages of unfolding, hints at what I mean when my title says “multibody spacecraft reconfiguration,” and the view of Saturn is just plain cool – and hints a little that I’m thinking about far-flung applications.
Here’s another thing I don’t do on my title slides: I don’t start my presentation by saying, “Hi, I’m Joseph Shoer, and I will be presenting on Simulation of Multibody Spacecraft Simulation through Sequential Dynamic Equilibria.” Why? Because my session chair just introduced me with exactly those words. I don’t need to repeat, and I don’t need to read off the slide – presumably my audience can do that for themselves. I say, “Thank you for the introduction,” and then I start right in.
Engage rant mode!
The vast majority of technical presentations I’ve seen include an “outline” or “agenda” slide. In general: I hate them.
I hate outline slides because they either convey no information I didn’t know already, or they convey very specific information that is entirely out of context and so I don’t understand it yet. Either way, they are a waste of time. In a 10-, 15-, or 20-minute presentation, saving thirty seconds to a minute can be quite important.
The outline slides that convey no new information have a bullet list that says something like Introduction, Background, Methods, Data, Results, Conclusions. You know, some variation on the standard lab report headings. If I’m listening to a presentation, I already know that you’re going to have an introduction and conclusion, and I already know that there’s going to be some kind of content in the middle. And if I’m at a technical presentation, then I already know that the middle sections involve explaining some experiment or model, looking at data, and extracting results. On top of the slide itself, one rule of presenting is that the speaker should talk about everything that appears on the slide. I don’t need the presenter to take the time to say things like, “At the end of my talk, I will conclude with some…conclusions.”
The other kind of outline slide, the one that the audience cannot understand, is the kind that tries to circumvent the lab-report headings by substituting in much more study-specific technical terms. This puts the speaker in a dilemma: if they just read the outline points, the audience won’t understand them. On the other hand, if they take the time to explain what each point means, they will end up repeating their presentation. Even if they do this well (and it’s my opinion that a well-done introduction should be solid enough to make such an additional “preview” unnecessary), there’s usually not much later on in the presentation to connect things back to the outline that ostensibly let the audience know the lay of the land. It’s like seeing the map for a road trip only once, before you get in the car, and then never again.
So: either the outline tells the audience that a presentation has the usual sections, or it tells them something that they’ll forget a slide or two later. In both cases, it’s a waste of time.
(Disclaimer: I have seen outline slides done well. In those cases the outline usually substitutes for the introduction. But they are so, so, so incredibly rare that I’m more than happy advocating the complete omission of outline slides.)
Slide Design and Layout
Here’s a typical slide I displayed.
I had four common elements on each slide:
- The Cornell seal and name of my lab, for branding.
- A brief list of the major sections of my presentation, with the current section highlighted. I find that this is very effective at letting the audience know where I am in my presentation and where I plan on going. It’s much more effective than, for example, a total slide count or a leading “outline” slide.
- A slide title. I go back and forth on whether this is necessary, given the moving highlighting in the section list above.
- A slide number.
The rest of the slide – and it’s quite a big area – is for content. And, in this case, I used that whole area for one thing. It’s certainly a spectacular picture, but I used this as a jumping-off point to talk about the Space Station and how it illustrates more than one application of spacecraft reconfiguration, the subject of my talk. It also illustrates the shortcomings of reconfiguration as implemented nowadays, since the Station’s robot arm is restricted to moving incredibly slowly.
You can see with this one how the black background helps with the space motif. It’s well worth the effort of color-inverting all my plots!
Often, I still end up needing to put a list on the screen. But a bullet list is not often the most desirable or effective way to do this. I have heard and read a number of designers who rail against bullet lists, and I agree with their reasoning: putting points in vertical order implies that each bullet is equivalent in some way, giving the points a parallelism that often doesn’t exist. (Check out the made-up example slide I led off with. Each bullet has a different kind of content. The bullet texts are not even the same type of phrase!) A list also implies some kind of order or hierarchy: the audience will read from top to bottom, making the first and last items in the list stand out.
Here’s the way I did it:
I put each list element in a little box, because they are separate concepts. The boxes also help me set off each item from the other items, making their mis-alignment very obvious. The message I was going for: this is a collection of concepts; they have something to do with each other by virtue of appearing on the same slide, but they are not arranged in list order and aren’t necessarily the same “level” of idea. I also went with a graphic, floating in space over the black background, that connects with several of those concepts. Below is another example, but this time I separated out the elements by color to imply some additional grouping.
Technical Content Slides
Of course, this presentation isn’t all for entertainment. (I estimate a good mix might be 1 part entertainment per 2-3 parts science and engineering for a technical conference. Contrast with a general-interest lecture, or what people like Neil deGrasse Tyson, Carl Sagan, Phil Plait, etc do.) But being engaging and understandable and conveying rigorous technical content are not mutually exclusive! Take this example:
I was explaining the Udwadia-Kalaba method for generating equations of constrained motion. One way to represent kinematic constraints, visually, is that a point representing a system has to move along a surface – which gave me a great way to use the slide as a visual aid to explain the concept. I think this would make for much faster understanding by the audience than spamming equations, too, because I get to say “the system has to move in a way consistent with the constraints” without having to explain all the terms in an equation. Still, it’s a complex slide with a lot of parts to explain, so I used the animation features in Powerpoint (simple fade-ins, nothing fancy, as a rule!) to bring them in a few at a time and explain them in sequence. Using the animations is also useful to me, in that it reminds me to explain everything on the slide and reminds me of the presentation order I decided. I knew I’d be presenting on my own laptop, so I didn’t have to worry about the animations porting over – in the past, I’ve used the trick of making each step in the animation a separate slide to make sure things go smoothly.
I do have the equation there, of course. And I took the time to point out all the important terms. But that doesn’t mean that this slide isn’t pretty! I saw many slides at the conference with similar content, but in Powerpoint bullet-list form.
Of course, the reason to give a presentation like this is to highlight some results. Often, this means graphs. Those results should be displayed as big and easy to read as possible. The black background helps for making things stand out, but there are certain necessities: big fonts and axis labels, in particular.
My favorite way to display results, though, is with movies. I mean, I’m talking about spacecraft made of modules that all slide and swing around each other to morph the whole spacecraft. I could make that extremely dry, but a good way to demonstrate that I’ve developed these algorithms and that they handle control of reconfigurable systems is to show it working. But it’s important to spend the time to put a polished movie together, to integrate it with the rest of the presentation, and to be familiar with its technical content so that I can use the movie to demonstrate my technical points. (Once again: visual aid.)
Believe me, engineers are suckers for cool movies. YouTube has a lot of hits for robotics research, for instance.
Making the presentation easy to read is especially important, and it’s worthwhile to keep in mind that reading off a screen and from a projection are different. On your monitor, with light beaming out towards your face, it’s sometimes worth it to use low-contrast settings to keep things easy on the eyes. But on a projection in a dim – not dark – room, it’s better to make everything stand out.
I like to stick to a pretty small color palette, with the exception of photos and movies, which look more natural. For high contrast against black, I used a lot of white, light grays for accents, green, yellow, and cyan. (Blue and red – 0,0,1 and 1,0,0 – on black are bad ideas. They can easily wash out in a dim room.) Color is a way to convey information, and if I don’t need that information, then I try to keep things black and white.
As with colors and contrast, the key thing with fonts is to keep them easy to read. The presentation slides I’ve been pasting use a combination of Eras Medium for headings, Candara for the section highlight bar, and Segoe for text. All of those are sans-serif fonts with easily discernible characters. I could simply have used Arial or Calibri, but I chose to break from the defaults as just another way to say, “my presentation is different from all the others you’ve seen!”
I have come to like placing minor-heading slides between the major sections of my presentation. Again, that’s a way to keep the audience in the loop about where the presentation is going. But I like them for an even more important reason, which is that they help remind me about the transitions!
I’ve heard a number of heuristics for how many slides should be in a presentation. Ten total, or one per minute, and the like. It’s hard for me to come up with a reasonable heuristic for myself, though, because I tend to simplify my slides a lot, meaning that there are more of them but I go through them faster. I ended up with 33 slides, presented in 20-25 minutes, at GNC, but about five of those were heading slides and there were a few groups of 2-3 slides that expounded the same concept, so “one concept per minute” might work to describe my style.
I always include an acknowledgment slide, because research is not usually done alone.
I also like to end my presentations with a repeat of my title slide (though I added in my group’s web site address), which lets the audience connect the graphic they first saw with the context of the rest of my presentation and reminds them who I am, where I’m from, and the title of my paper in case they want to look it up later.
In addition, I keep a bunch of backup slides on hand. Since my presentation style focuses on giving highlights, it’s entirely possible that I’ll get questions about the details; so, I make up a bunch of slides (or paste in from previous presentations) about my prior work or specific details, especially if I can anticipate what questions the audience will ask. If I use the backup slides, I get to look especially well-prepared!
Powerpoint contains this neat feature that lets you make slide templates (in Powerpoint 2007, look for “View Master” under the “View” ribbon). I get a lot of leverage out of the master template slides to get a consistent theme for my titles, headings, and content slides. Slide masters are also an easy way to get the section highlighting in the mini-outline in my header to work without lots of headachy monkeying around with tons of colors and styles on each slide individually. I typically base all my masters on the “blank” template, without any automatically-generated text box placeholders, so I can look at each slide as an empty canvas.
Okay, I’ll get off my soapbox now. Maybe I will make some of my Powerpoint presentation templates available. My goals are both clarity in conveying content and engagement of the audience. I try not to sacrifice too much for one or the other, and have ended up at a distinctive, minimalist style. From the feedback I’ve received, it’s generally successful.
I have to give a bit of a shout-out here to the Williams College Physics department, which requires its research students to do a lot of presentations. Those prepared me very well for grad school. There’s also an incident that stands out in my mind in which physics profs Daniel Aalberts and Dwight Whitaker did a joint physics colloquium in which they (intentionally) demonstrated everything that a presenter could do wrong. If I ever am in a position to teach students about presentations, I’d love to play with that!