Free software for biologists pt. 4 – presentations

This post is going to strike a slightly different note to previous pieces on software tools for writing, handling data and preparing figures. In each of those I emphasised the advantages of breaking away from the default proprietary software shipped with the average PC and exploring bespoke options designed for scientists. In the case of giving talks or lectures, I’m going to argue for the complete opposite position: it’s not so much what you use, but how you use it.

When delivering a talk, the slides that accompany it are visual aids. I’ve emphasised that term because its meaning has been lost through repetition. The key word is aids. The slides are there to support and enhance the understanding of the audience, and to back up what you say. They are not supposed to be the focus of attention. The slides are not your notes*.

What’s more, slides cause problems more often than they dramatically improve a talk. An ideal talk is one where the audience receive the message without anything getting in the way. How many times have you walked out of a conference talk thinking ‘great slides’? Perhaps never. On the other hand, how many times have you seen a perfectly good talk ruined by a distracting display or computing failure?** For me, that’s at least once a session.

With this in mind, I recommend starting to plan a talk with a simple question: do you need to have any slides at all? Yes, I know, I’ve just challenged the default assumption of almost every conference presenter these days. But I’m absolutely serious. Start from the perspective of thinking what you are going to tell the audience, in normal speech, while they look directly at you and listen to what you say. If you can convey all the information you need to  without slides (or by using other visual aids, such as props or exhibits) then there is no obligation to have slides at all.

Next ask yourself what elements would benefit from being presented visually as well. Note that I’m explicitly trying not to write the talk around the slides, but the visual aids around the talk. Once again there might be no need for slides — you could work through equations or models by sketching them on a blackboard. Nevertheless, for certain types of information, slides are the best means to present them. Data figures, photographs, diagrams, maps and so on are going to need to be put up on the big screen. Note that none of these involve much text, if any.

When you start from that perspective, the software you choose to prepare your slides should be the one that permits you to most clearly present your figures without distracting clutter.


Slides are there to help the audience understand your points, not to replicate the talk. Only include the bare minimum of text and be prepared to walk your audience through the details.

With this in mind, PowerPoint is fine for producing lecture slides, and easy to use. The main challenge is changing all the default settings to be as plain and simple as possible, and resisting the temptation to use features that only serve to distract the audience from your intended content (animations, background images, sound effects). These should be used sparingly, and only if they improve the transmission of information***. Remember: slides are there to inform, not to entertain. If you don’t want to pay for Powerpoint then the free LibreOffice Impress will do all the same things and serves as a direct replacement.

An online alternative is slides, which adds the neat trick of allowing remote control of presentations from a second computer or your mobile phone. Another choice is reveal.js, which is free for basic users, but if you want to download a copy of the presentation or collaborate with a colleague then a subscription is required. Being willing to write a little code helps too.


If you’re using LaTeX then an alternative is the beamer document class. powerdot appears to do the same thing but I’ve never used it. The usual caveat about LaTeX applies — if you’re not already using it for everything then the time investment for presentations alone won’t be worth it. I have also yet to find a way to embed videos directly into slides.


All my slides are prepared in LaTeX using the intridea beamer theme. I like the look of them, but it takes time and expertise to set up. You could achieve something similar with much less effort.

One good reason to move away from Powerpoint or its analogues is frequency-dependent selection. You can stand out from the crowd simply by virtue of using something different. By the end of the first day of a meeting people are already suffering from Powerpoint fatigue, which makes anything else a pleasant relief.


To really change style and impress your audience, try Prezi. This is a different way of visualising your talk, and some time investment is required to get it right. As with Powerpoint, there are many tricks and decorations that can be inserted, but which will distract from the information you’re trying to get across. Particularly try to minimise use of the ‘swooping’ movement, which can induce nausea in your audience.

The two main disadvantages to Prezi are that you need to be connected to the internet to use it, and that the free version requires your presentation to be visible online. The first is seldom an issue, the latter only matters if what you’re showing is somehow private or confidential, and if so then why are you presenting?

In general I don’t submit posters at conferences, though there are many good reasons to choose a poster over a talk, and a lot of guidance on how to do it well. I’m not going to repeat this because I have nothing to add, but also because I have no personal experience to draw from, and can’t therefore recommend any particular software.

* This is true for most public, professional presentations. Lectures for undergraduate students are a different matter though, at least within my experience. Many students now assume that the slides are the notes, and expect to be able to reconstruct the material from these alone. Some lecturers provide printouts of slides as their handouts. You can debate whether this means you should include more material on your slides to serve this function, or make a stand, expect students to take their own notes, and risk complaints.

** Many years ago — long enough for the scars to have healed — a collaborator of mine presented her work at a major international conference. It was a hot topic, and the theatre was packed. We had gone through the talk together the previous night on her laptop and I’d not seen any problems. But on the day it turned into a nightmare. For some unknown reason, every animation (in Powerpoint terms, that means lines or other elements appearing on the screen) was accompanied by a sound effect. Distorted by the conference room speakers it was transformed into something akin to the bellow of a caged animal. This happened every time she clicked, all the way through the talk. Even worse, none of the videos worked. Her evident mortification was met by the awkward, sympathetic unease of the audience. Everyone remembered that talk, though not for the right reasons.

*** A good general rule is: can I save it as a pdf file with no loss of features? If you can then do; not only are they smaller, but they’re more stable, and guaranteed to look identical on whatever computer you need to use. If there are features that would be lost then think carefully about whether you really need them.


5 thoughts on “Free software for biologists pt. 4 – presentations

  1. ScientistSeesSquirrel

    Great advice, Markus. I’m not sure I’d go text-free, but I do know that less text (than I use!) is better.

    One thing about Prezi – I’ve seen many talks done with Prezi; ONE of them was good. The temptation to use swooping and all kinds of other annoying effects, and to use non-linear presentation structures, seems to be nearly irresistible. Of course one can give a good talk using Prezi – by turning off all the distracting stuff – but then I guess one would wonder why use it at all?

    Liked by 1 person

    1. Markus Eichhorn Post author

      You’re quite right: just because Prezi has different unnecessary animation tools doesn’t justify using them. There are some ways it can be used effectively; for example by zooming in on parts of a map, or elements in parameter space when taking a multi-level approach to a problem. It’s all about moderation though.


      1. ScientistSeesSquirrel

        Moderation! Indeed. And I like your zooming-on-map example: that’s when a swoop/zoom has a functional purpose that makes presentation clearer, rather than just being a dazzler that distracts.


  2. Pingback: Free software for biologists pt. 5 –operating systems | Trees In Space

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