Public Speaking:
Some Dos and Don'ts

By Dave Finley


Good communication is essential to science. Oral presentations are a traditional and heavily-used means of scientific communication. A working scientist may hear hundreds of technical talks in any given year, and may be called upon to give many as well. Public speaking is an essential tool of the active researcher, yet an amazing number of the talks we hear are far less effective than they should be. We've all suffered through boring, droning sleepfests that disguised what really was exciting science. On the other hand, we've also seen well-delivered, energetic talks that made exciting something that we thought would be deathly dull.

I've probably heard a few thousand scientific talks over more than two decades, and seen little improvement in the overall quality of presentations. There have been some bright spots. PowerPoint and other presentation software has, mercifully, made the hand-scrawled viewgraph obsolete. The slides we see today, produced on computers, may still be boring, but at least they usually are legible. In speaking, it appears that the wretched "you know" has peaked and is in decline, but other annoying habits have arisen to fill the gap. The problems that plague most presentations largely are simple, basic things that could easily be remedied. Here are some thoughts about how to make our presentations much more effective and pleasing to our audiences.

Planning Your Talk

Do decide what the purpose of your talk really is. What is the "take-home" message you want to give your audience? Organize your talk accordingly, focusing sharply on your intended message.

Do prepare a talk that will fit within the time limit you're given. That includes allowing time for questions from the audience. Rehearse with a stopwatch if necessary.

Don't forget that studies show an audience can remember only three or four things you present in a talk.

Don't distract from your message by including peripheral topics or excessive arcane detail.

Don't forget that any lecture is a performance: you must work to get your message across.

Some Basics

Do show some enthusiasm and energy. If you're not excited about your topic, why should the audience be?

Do face your audience. If you need to see your slides, then look either at the overhead projector in front of you or at the screen on the computer running your presentation. It's not only rude to turn your back on your audience, but it also means you're speaking into the screen or the wall and making it hard for them to hear you.

Do speak loudly enough to be heard by the entire audience, even those in the back row.

Don't keep jumping back and forth through your slides. Either reorganize your talk to avoid this or duplicate the needed slide in the second place where it fits.

Don't start to change a slide, then stop halfway. Either change it or leave it.

Don't fidget nervously in front of your audience. Make your movements and gestures purposeful.

Don't stick your hands in your pockets, hook your thumbs under your belt, or engage in other creative diversions.

Words, Phrases, etc.

Do clearly define any terms that may not be familiar to your audience. Remember, they're probably not all from the same specialty as you!

Do keep acronyms to an absolute minimum. They're like speedbumps to listeners unfamiliar with them.

Don't start sentences with "So."

Don't end sentences with "right?" or "OK?"

Don't apologetically introduce a topic with "Just real quick," "Briefly," or similar words. What that tells your audience is that "this isn't really important or relevant, but I'm going to inflict it on you anyway."

Laser Pointers

Do use a laser pointer to direct the audience's attention to the part of an image or graphic to which you are referring when the area of interest is not going to be obvious to them.

Do put the laser pointer down when you aren't using it (which should be most of the time).

Don't wave the laserpointer all over the screen as you talk. You're going to give your audience a headache as their eyes jerk all around their heads trying to keep up.

Don't use a laser pointer to point to text. Your audience is as capable of reading as you are. Do you still run your finger under the words as you read? Neither do they.


Do answer questions as succinctly and briefly as possible. Remember, there may be only one person in the audience interested in a specific answer.

Do remember that "I don't know" is a perfectly good answer. You needn't go into a five-minute explanation of why you don't know. If you're working on answering the question, just say that.

Don't use a question as an excuse to bring up the dozen slides you cut out of your talk in order to meet the time limit you were given.

Don't go rummaging through your slides to answer a question unless it is absolutely necessary (and it usually isn't).

Don't hold "private conversations" with questioners in the front rows. Make sure everyone in the audience knows what the question is (repeat it if necessary) and can hear and understand the answer.

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