How to give a talk (about science)

How to give a talk? You know what material you want to present, but how will you do it? You want to be clear and logical, but not cold and clinical. You've seen so many bad talks: how do you avoid that? These suggestions were written for a students who have to give short (5 or 10 minute) talks on a topic that they have researched but who may never have given a talk before at university.

Timing is critical

It is extremely important not to go over the time limit. You must be fair to other speakers and to your audience. Everyone hates a speaker who rambles on for too long. It is preferable to finish early than late - an early finish will leave more time for discussion - or even let the class/audience finish early.

The ability to present a persuasive argument in a short time is a very useful one, and its use goes far beyond science, so you should treat this exercise as useful practice in gaining or improving that ability. Here you have a limited time. Make each point count.

Text or notes?

Most audiences prefer to listen to someone speaking from notes (or even from memory) to someone who is reading a prepared text, so you should only do the latter if you have rehearsed speaking from notes and you really find it impossible. The great advantage of notes is that you have time to make eye contact with your class. This is very important for effective communication.

Rehearse!

In any case you should rehearse your talk against the clock. It may help to rehearse it with a friend who can give you advice - for a 5 minute talk it will only take your friend 5 minutes to listen to it! Rehearsing out loud a few times can make a big difference to the final version of a talk: you will find the awkward phrases and ways to avoid them, and you will find and refine the neatest and most convincing way of putting your case. If you do not rehearse, you will probably find the chair imposing the time limit while you are still muddling through your introduction.

Start and finish well

Many people find it useful to learn by rote the first and last sentence of the talk. It is important that your first few sentences are clear and confident and proceed without stopping. For a start, this will make you feel confident and your audience feel comfortable. Further, once you have given your audience something to think about, you can afford to pause - the audience will appreciate the thinking time. (It is worth remembering that a pause which feels like ages to the excited person talking may really be only a couple of seconds to the audience.) It is useful to remember a good closing line so that the audience knows that you are finished - it is a bit awkward if you stop talking that the audience is unsure whether you have finished or not. If you can make the last line memorable, you may give them a good line to take away.

Language:

Anyone who has ever given a talk in a language that is not his/her native tongue will know how much more difficult it is. For this reason, native English speakers are always very supportive of, and usually impressed by, those speakers whose first language is not English. Your thinking is more important to us than your speaking.

Technology:

How to show figures or tables or other material that is not easy to put into words? There are several options:

Blackboards and whiteboards are great for this, but the art of explaining something while simultaneously drawing or writing on the blackboard takes a while to acquire. So use these if they are there, but only for the most important parts. If you have the time before the talk to put up your material, then these are options. If not, then you may not have time to use them effectively in a short talk. Remember that they are there, however, if you need them to answer questions.
Draw/write/print on a sheet of paper and hold it up. This works well for small groups, provided that you don't try to squeeze too much information onto a sheet. After you have shown it, you can pass it around in case people want to look at details.
Handouts. Depending upon the size of the class, you might consider handing out copies of a single sheet of paper. On this you could put small versions of any information you want to display. You might even want to put on the same sheet the references for furhter information. Don't waste paper. First, you don't need a copy for everyone in the class: they can share, and they probably don't all want a copy to take home. Second, don't simply photocopy lots of possibly relevant information and hand it out. Be very selective and restrict yourself to one sheet.
Data projectors. My advice is not to use these for a short talk in physics. For a long talk that involves animations that are central to the explanation, not just decoration, or for short movies and multiple soundfiles, it can be useful. Unfortunately, most users of this technique use distracting animations, colours etc. Powerpoint is most widely used in disciplines in which the medium is relatively important in comparison with the message, and you don't want to give that impression in science. Further, it is made by a company famous for wasting your time. Putting in equations is difficult and slow, compared to writing them by hand. If you must use it, it is worthwhile taking time to disable all of the distracting effects like "fly in", "break up" etc—these make you look like an unsuccessful middle-manager.
Recordings, sound of video, will rarely be used in a short talk. If you need them in a longer talk, make sure that they are loaded beforehand into the computer you are using, that it has the right software to play them, and that your files can be found quickly.
Demonstrations can be very effective, but are often impossible. However, if there is something simple (and portable and safe!) that you can demonstrate, or let the class demonstrate, then this is very likely to make your talk more memorable.

Do not let the length of this discussion of technologies make you think that you must use them. For a short talk, your voice might be all that you need to make an excellent presentation. Good luck!

A list of some of Joe Wolfe's educational web sites.