Things you should (not) do in a talk – Part 3

kandinsky Previously on Much Bigger Outside, we discussed how to manage time and define the content of a talk. In this post, we will discuss how to prepare good slides.

3. Talking about slides

Visual aid through projected slides is an essential part of every scientific talk. But often, we see slides that are awfully ill-prepared. They not only don’t help to deliver the presenter’s message, but sometimes even disturb it. So, here are some tips about what to do (and what not to do) in the slides.


Before creating your slides, decide about style and color scheme. Use the same style throughout the whole presentation. If you use Power Point, work on a good set of Master Slides to define standard fields and styles for titles, logos and working area.

Bear in mind that a beautiful color scheme on the screen, may look very bad when projected. Choose colors always aiming at maximizing the contrast.

For the background, you can have any color as long as it is white. Background pictures and patterns are often disturbing. Gradients and even uniform colors are dangerous. You never know what will be the quality of the projector at the conference site.

Fonts should be in contrast with the background. Text should not be smaller than 18 pt. Take care that even small elements like axis labels of graphics are least 14 pt.

Use standard fonts that people are comfortable with. I prefer fonts without serif, like Arial. But this is subjective, Times will do a good job as well. If, however, you think that Comics Sans will make you look clever and buoyant, think twice, they will make you look outdated and childish.


The most common problem I see in slides is excess of information. Slides are for free, there is no need to overcrowd them!

You should have no more than one or two central pieces of information in the slide.

Sometimes people like to put a lot of info together maybe hoping that they will show a synthetic way of thinking. Nope, they only show a confusing way of thinking.

Check the slide below at left:


A overcrowded slide (left) must be split in multiple slides (right).

It is a case where the public either doesn’t know where to look at, or get distracted by some of the multiple elements, or both. It is much better to split that slide in four, like that in the right figure above.

Sometimes, you really need to show multiple elements in the same slide. In such cases, you may adopt a strategy like in the figure below. In that slide I wanted to illustrate the differences between four different things. I used the slide at left to discuss a first case. Only after that I put all four elements together in the slide at right.


If you should show multiple elements, go in parts.

Keep texts short. Think of yourself in the public: do you really read full long sentences? Probably not. Why do you expect that other people will do so?

Same for bulleted and numbered lists. Keep them short and clean. Having more than 6 points in a list is bad: it is distracting and makes you spend too much time in a single slide, which is boring.

Figures and Tables

Take special care of figures. A good figure for a paper is not necessarily a good one for a talk. Look at the next example:


Work on your figure to make them well fit for a talk.

The figure at left was taken directly from a paper, even with its caption as a lot of people like to do. It is a bad figure for a talk. Labels are uncomfortably small, it’s a boring gray scale, and there is too much information. At left, I worked to solve all three problems. In particular, I left only the two curves that I wanted to discuss in the talk.

Concerning tables, if you can replace them by graphics or charts, better. The public will thank you for that.

But if really need to show tables, make them fit to a presentation.

I see people showing tables like the one below at left. It usually comes with a warning: “I won’t explain all this in this talk; you should look only at here and here…”.


Work on your table to leave only what is strictly necessary.

No help. No one can focus on “here and here” with tens of numbers floating around. If you know that only “here and here” are important, make a simpler table with them alone, like the one in the figure above on the right.


You have three good and legitimate reasons to cite references in the slides:

  • To give credits;
  • To allow the public to look for more information later;
  • To show yourself off.

I would need a PhD in psychology to understand why some speakers show references like the way in the slide below at left. They just don’t help with any of the three reasons!


References: simplify them.

If you could read those references, they would look like:

MB and H. Lischka, J. Am. Chem. Soc130, 6831 (2008). C. M. Marian, J Chem Phys 122, 104314 (2005). Perun, Sobolewski, and Domcke, JACS 127, 6257 (2005). MB, J. Am. Chem. Soc., doi:10.1021/ja505387c (2014). MB, A. J. A. Aquino, J. J. Szymczak, D. Nachtigallova, P. Hobza, and H. Lischka,PNAS 107, 21453 (2010).

Apart of the small fonts, what else is wrong with them?

Basically, everything:

  • They don’t have consistent format. This would speak badly of my organization skills.
  • They are too many. People won’t have time to take note.
  • They show only my initials. If you already won a Nobel prize, then you can afford to lay only your initials. If not, chances are that part of the public won’t even remember your name. Humbleness here won’t help you.

Then, what to do about references:

Choose a short format easy to be taken in a note. Delete initials, dots, and use short journal abbreviations. Too long list of names may need an “et al.”, but the first author, the boss, and yourself should be in there.

Cite only those really needed references. You have 10 papers on the topic. You cite all of them. Your show-off goal was accomplished, but none will bother to take note of them.

In the example above, after these tips, the references turned out to look simply:

  • Barbatti, Lischka et al., PNAS 107, 21453 (2010)
  • Marian, J Chem Phys 122, 104314 (2005)
  • Perun, Sobolewski, Domcke, JACS 127, 6257 (2005)


Animations are good, but if are going to include them in your presentation, you need extra-time to rehearse.

How many times don’t you see people talking and talking and then–when they move to the next slide–a lot of animations, which were supposed to guide the discussion, starts to pop out?

This clearly shows that the person was not “intimate” with his or her presentation.


And speaking of being “intimate” with the presentation, in the next post, I will discuss how to present the talk.


  • If you enjoyed this post, follow the blog by signing up in the sidebar. Leave your comments or like below. You can also follow me on Twitter.
  • Do you have other tips about how to prepare slides? Share with us.
  • The painting at the top is the Kandinsky’s “Complex Simple“, 1939.
  • Not convinced that you should give up on Comic Sans? Check this V-Sauce video.

Categories: Productivity, Work Organization

Tags: , , ,

3 replies

  1. Could write a post about how to prepare TOCs sometime? 🙂

  2. Great tips.
    I should also mention that if you have videos embedded in your presentation, TEST them from inside the presentation on the computer you are going to use for the lecture. I have encountered many times were the movie didn’t work and the lecturer wasted lots of time trying to figure it out.
    Also, have backup slide of image from/of the movie, just in case…

    Also, if you know that you are going to use a computer different from yours (e.g. mac vs PC, or old vs new versions of OS or PPT) check that everything looks fine. I’ve encountered several times when symbols & special characters were not shown properly.


  1. Things you should (not) do in a talk – Part 4 | Much Bigger Outside

A penny for your thoughts...

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: