Preparing a Five-Minute Talk

Step up to the mic.

There are a suite of quotations — attributed to Winston Churchill, Mark Twain, Woodrow Wilson and others — that go approximately like this:

If you want me to speak for two minutes, it will take me three weeks of preparation. If you want me to speak for thirty minutes, it will take me a week to prepare. If you want me to speak for an hour, I am ready now.

The origin of the sentiment is tough to pin down but, the consensus remains: preparing a short talk is far more difficult than a longer one.

Last week I delivered a brief talk to Fellows of the Royal Society over Zoom. My instructions were short — five minutes, no slides — and I chose a topic I like to keep in my back pocket, the physics of the Boston Molasses Flood. Honestly, I’d already delivered a great five-minute Ignite talk on the Flood but that format explicitly relies on slides, so it wasn’t helpful for this new talk. I also have my YouTube video (linked above), which is about five minutes long, but similarly relies on visuals for storytelling.

Telling the story without visuals is a very different situation. So I started planning my talk with resources I already had; I watched my video and took notes. I wrote down numbers and details. Initial wave moved 55 kph. Tank was 27.4 meters wide and 15.2 meters tall. I noted eyewitness quotes I wanted to use.

“It looked like a tidal wave, and I never thought of molasses at the first of it. It looked to me like boiling oil — hot oil. It was curling like a wave at the seashore and looked frothy […]” — William H. Connors

With these tidbits at my fingertips, I turned to a new page and began sketching out my talk. Five minutes isn’t long, so I knew I needed a concise format. I opened with a description of the setting, using vivid details to evoke the right image: The North End neighborhood of Boston, mid-January 1919. An unseasonably warm day at 4 degrees Celsius following a frigid streak twenty degrees colder. Children are playing in their school lunch break. Freight workers shout to one another. Firefighters settle in to their lunchtime card game.

Carrying on, I described the molasses tank, its rupture, and the devastation it caused. Around 1pm a thunderous crack split the air and the tank broke, spilling enough molasses to fill 3.5 Olympic-sized swimming pools. Buildings were knocked off their foundations. Wooden ones got turned to kindling. The elevated railroad’s steel beams buckled. 21 people killed, 150 injured.

Even without slides, this opening painted a portrait of the disaster, and it hooked my listeners. In about 1 minute and 30 seconds, I laid out much of the event and dropped some breadcrumbs I could pick up in later sections. Narratively, this introduction is in medias res, meaning that I start my story near the climax rather than laying everything out chronologically. The technique creates immediate interest for the audience, which is especially useful in a short time constraint.

With the basic story laid out, I stepped back to answer an obvious question my listeners would have: why was this tank there? I blended the answer to that in with a follow-up question — how did the accident happen? — over the next minute of the talk.

Then, without explicitly saying so, I launched into the physics of the accident and my scientific (rather than historical) research into the subject. In my notes, I call this section “What did it look like?” For the first thirty seconds, the molasses acted like a tsunami. Here’s where I got to use my eyewitness quote and point out that he’s describing turbulent molasses, something neither I nor my audience have ever witnessed. I cited the historical estimate of that wave’s speed and explained the work I did that confirmed the plausibility of that velocity.

Continuing onward, I described the physics following that initial wave. After the first minute or so viscosity takes over and the flow seeps, but that’s no better with everything drenched in molasses. I went on to describe rescue efforts and the problems created for both rescuers and victims as the temperature dropped and the molasses’s viscosity rose.

Finally, with about 30 seconds of the talk remaining, I laid out a couple of important conclusions: The accident sounds surreal and laughable but digging into it revealed amazing historical and scientific depth. And the Molasses Flood remains relevant today when natural disasters like mudslides can quickly transform mundane materials into deadly ones.

The audience enjoyed my talk and had plenty of questions to fill the Q&A. Though the five-minute limit required leaving out many details, that brevity guaranteed lots of details I could add in response to questions. Personally, I love this set-up because it makes the Q&A into an extension of the talk that focuses specifically on the audience’s interests rather than requiring me to guess what they want to hear about.

The key to talks this short is determining what material to cut out. I make that decision based on the key message for the talk; any detail that’s unnecessary to support that message goes on the chopping block. Often this means killing your darlings but in a time-constrained talk, the time limit rules above all. Anything that doesn’t help you tell the story within the time limit has to go.

With the bones of the story in place, it’s time to practice. It’s here where short talks have an advantage over their longer brethren. I don’t have the time to practice an hour-long talk five times, but doing so with a five-minute talk is easy. After my first few attempts, I had a sense for exactly how much embellishment on my notes I could get away with while sticking to the time limit. With a few more rounds, I was running smoothly and hitting my timing consistently.

When I was a student, I would practice a short talk like this ad nauseum until I could (literally, according to my roommate) give it in my sleep. Nowadays I’m more relaxed with speaking, and I trust myself to perform well once I get going. Occasionally, that means practicing my talk’s opening more than any other part; once that section is down, momentum will usually carry me through the remainder. For this particular talk, I ran through the full talk 6 – 8 times total.

In the end, I did not have two weeks to prepare my five-minute talk. Although I got the heads-up about the talk a week in advance, my schedule didn’t allow me to truly sit down and prepare until about 24 hours ahead. When I was less experienced as a speaker and storyteller, such a short prep time might have been disastrous. But with a comfortable subject, references I could lean on, and experience with short talks, it was doable, though anxiety-provoking.

So how long does it take to prepare a five-minute talk? There’s no easy answer. It depends on many factors: how familiar you are with your subject, how comfortable you are with speaking, how well you know your audience, and how easy you find it to construct a succinct, understandable, and interesting story. One thing is certain: it will take far, far longer than the talk’s run-time.

As always, I hope a glimpse into my own process helps you in yours.

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(Image credit: K. Reinholdtsen)

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