Demonstration, Performance

Magical Balancing Can

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I suspect many of you who watch the above video will know exactly how it’s done but it’s not immediately apparent to everyone, especially if you choose to present it in a way that isn’t quite honest about what’s going on.

I use this demo in my teaching to introduce the idea that an object will topple over if the line of action of its weight lies outside its base. I usually present it as a challenge: I start off with two identical (apparently) empty drink cans on my desk (yes, I know the ones in the video have slightly different designs). I offer one of the cans to a student and challenge him or her to balance it on the edge of the base. I tell them I’ll try to do the same with the other can. I make a big show of concentrating, then reveal that I have managed to make my can balance while the student’s can keeps falling over (this usually gets a gasp of approval – as I think the video shows, the can balanced on its edge looks quite disconcerting). After the initial surprise at my being able to balance the can, the students usually guess that something’s not quite right.

I think this demo works well presented as a “magic trick” because it captures students’ attention and provokes the question “what’s going on?” or “how does that work?” and that’s when the discussion begins…

UPDATE: I’ve had a couple of responses to this post on Twitter and elsewhere. I should perhaps have said that using this type of approach may not be suitable for all teachers – you have to be comfortable with the way you present a demo to a class and if showmanship isn’t your thing there’s no point forcing it (although I’d argue that this particular demo requires very little in the way of showmanship to present as a “magic” trick). We touch on this issue in our forthcoming film Demo: The Movie.

A teacher contacted me saying it was a shame I didn’t provide an explanation as it would make it easier for teachers to do the demo if they knew exactly how to do it. So, here’s the trick: place a little water in the can you want to balance before your lesson. The easiest way to judge the correct amount of water is to hold the can in the balanced position then pour water into the can until you feel it just balances. Alternatively, you could pour in liquid wax and let that set so that you have a pre-prepared can that you can keep in the equipment cupboard.

Demonstration, Discuss, Get Set Demonstrate

I’ll show you impact

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Ah, the joy of modern media. You can publish a film one week, and the following week you see a tweet from a teacher who’s incorporated ideas from it into their lesson. Even better: they post a photo of their students exploring ideas around air pressure via the approach in the film.

Photo above from Tom Sherrington, @headguruteacher. Huge thanks for allowing us to repost, Tom – it’s a delight to see this stuff getting used.

Get Set Demonstrate

Get Set Demonstrate

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Monday’s posting of the visking tubing film was the last of the demo videos we made to support Get Set Demonstrate. The culmination of the project comes during National Science & Engineering Week: on 20th March 2014, The British Science Association are coordinating a national Demo Day.

Teachers are invited to join in simply by performing a demonstration to their classes on the day. Sign up at the BSA’s site to show your intention: take the pledge! There are equipment discounts from Timstar up for grabs, too.

We’re not quite done with our contribution, however. Our long-heralded Demo documentary will hit the web in early March.

Discuss, Performance

The thrill of the audience response

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My name is Paul. I’m a reaction junkie.

Like many science communicators who present demonstrations, I admit to getting a thrill from being able to provoke and orchestrate extreme emotional reactions from my audiences about my subject. The problem is, however, that like any addict, I am driven to want a larger and larger fix. The buzz is intoxicating.

This drive can unconsciously fool us into only valuing the most visible and audible emotional responses from the audience.

Take chemistry shows, for example. Chemistry demos are the shock jocks of the science demonstration airwaves. They viscerally grab attention with their flashes and bangs, but most don’t lead to any meaningful insight into the underlying concepts. Chemistry demos are bewitching to a reaction junkie.

The irony is that I genuinely believe that some of the most powerful audience reactions to live science demonstrations can be the least obvious – e.g. curiosity, wonder, and an intellectual joy of understanding. I’ve spent years of my life researching just this conviction. Yet the overt reaction drug still pulls. That is its danger.

They say admitting it is the first step to overcoming the addiction.

I am a reaction junkie.

But I’m trying to do something about it.

Demonstration, Get Set Demonstrate

Modelling digestion using visking tubing

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This is the second Biology film we’ve made as part of the “Get, Set, Demonstrate” project. One of the films we were asked to look at was “Making Poo: The Digestive System” but we felt that this was not what we would strictly call a “demonstration” of digestion (since no actual digestion takes place), but rather an illustration of the process. Instead, we chose to make a film about using Visking tubing to model digestion and use it to explore the reasons why you might choose to carry out a demonstration of an activity which can be (and often is) done as a class practical.

Get Set Demonstrate logoThis film was produced for the Get Set Demonstrate project. Click through for teaching notes, and take the pledge to perform a demonstration to your students on Demo Day, 20th March 2014.

Demonstration, Get Set Demonstrate

Chip pan fire

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No other film in this series provoked more discussion and argument than this. Mostly from me. It’s a classic demo and was highly-requested in the nomination stage of Get Set Demonstrate, yet I argued against filming it.

For many years I made essentially all the science programmes that went out during the UK’s teatime ‘children’s television’ window, and there were only a few demonstrations I flat-out refused to show. This was one of them. You can show a safe method, you can treat the science with due respect… but with video you have precious little knowledge of your audience. You can’t tell when their attention has drifted away and they’ve maybe missed a crucial detail, you can’t be 100% certain of the message they take home, and most importantly you can’t guess what they might be tempted to try for themselves.

In person, the heat from the fireball is impressive: on video, it’s the size of your TV, or a YouTube window, or your phone. And it’s cold.

Film-makers can’t be responsible for the behaviour of their audience (discuss, 20 marks), but in this case the risk is very, very high. If 100,000 children saw the demo in our show, and 1 in 1,000 tried it themselves, and 1 in 100 set the curtains alight… that’s not something I ever wanted on my conscience. It’s not that the demo is too dangerous, it’s that it’s too easy. It’s trivial to perform it yourself in a kitchen, and the results can (and will) be catastrophic. So I never filmed the demo. Until now.

Others on the team eventually convinced me, using effectively the same argument applied backwards. The demo is straightforward to reproduce, and reproducing it is dangerous. Knowing that – understanding how and why oil fires are dangerous – might just save someone’s life, and for that reason alone, the team argued, this demo should be known and used in schools, and hence we should make this film.

I’m glad we did.

Three quick notes:

  1. In a UK school, follow the CLEAPSS guidance (Scotland: SSERC). As a teacher or technician you should consult CLEAPSS as a matter of routine before attempting hazardous activities, and where they issue standard guidance (as here): follow it. ScienceDemo.org doesn’t have access to the CLEAPSS archive so we can’t link directly to the resource, sorry, but you’ll find it easily enough.
  2. The formal government advice on how to react to a chip pan fire in the home is: get out, stay out, and call 999. It’s no longer considered appropriate to attempt the ‘damp tea-towel’ remedy yourself: the casualty rate is too high. We should have mentioned this in the film.
  3. In person, our fires were a little underwhelming, with the water often putting the flame out quickly. We’ve cut around that for the film, but speaking to other demonstrators subsequently it seems we were probably more assiduous than strictly necessary about turning the gas off the instant the flame caught. Give it a few more seconds and you’ll get a more satisfying fireball, we’re told. Do see Bob Worley’s comment below about one-upmanship, however!

Get Set Demonstrate logoThis film was produced for the Get Set Demonstrate project. Click through for teaching notes, and take the pledge to perform a demonstration to your students on Demo Day, 20th March 2014.

Theatre, props and explanations, oh my!