Category Archives: Discuss

Eddy currents

Alom and I are filming at the moment, hence things being rather quiet around here. However, the above caught my eye. This demo is typically done with a long length of copper pipe, and the magnet takes many seconds to fall through. It’s effective on a stage.

The tall narrow pipe, however, is precisely the wrong shape to film, and on video the demo doesn’t work so well. This shorter length of fatter pipe, with an appropriate magnet, has more impact on camera.

Same principle, same demo… but different treatments for different audience contexts. So, lessons for us all:

  1. Don’t assume that the way you’ve seen a demo performed is the best way. Always look for improvements.
  2. It’s not just the demo that matters, it’s the way you use it.

That separation of ‘content’ and ‘treatment’ is, for me, an absolutely key concept.

Tip of the hat to my dad for sending this in.

The gloves conundrum

UCL chemist and demonstrator extraordinaire Andrea Sella, on his blog:

the wearing of gloves in the lab may, counter-intuitively, put us, our students, and our fellow lab workers at greater risk than riding their flasks bearback.

Do read the rest of his post, and likely the rest of his blog too.

I should talk to CLEAPSS about this sometime – Andrea’s comments on gloves make a lot of sense to me, but I’ve no idea what the standing advice for schools is. Ah, the simple life of not actually being a teacher.

Precision vs pedantry

Over the last few years, making all these demo films, I’ve found myself thrust back into the world of school education. It’s a bit of a shock. I’m young enough to have taken GCSEs myself, but old enough to have been in the first year to sit them. Much has changed.

One thing I find slightly baffling is the obsession with extremely precise terminology. There’s a natural inclination to precision in the sciences, but some of what I’ve seen veers towards the obsessive. It’s not precise, it’s pedantic. And it’s nerve-wracking. I can’t write a sentence of script without the fear of somehow mis-stepping, of treading on some unseen toes and bringing down some unrelenting diatribe about how you can’t use that specific word there, only this one.

Now, I’m old enough and weary enough to battle through such pressures. There are also times when I can dimly recall enough of the physics I once did to be reasonably certain that not all of the advice I receive is… umm… correct.

But if I find myself staring at an explanation with that stomach-knotting dread of you’re doing it wrong, how is a twelve year-old supposed to cope? Respect due, we’re raising them tough these days.

My assumption is that pedantry has crept in because it’s quicker and easier to assess whether the student can recite rote-learned material accurately than it is to judge their understanding against the examiner’s (also-flawed/incomplete?) knowledge.

But that really is an assumption. So, some questions:

  1. Am I right that school science is increasingly pedantic?
  2. Does being able to parrot a very particular definition demonstrate understanding?
  3. …or am I falling into the category of “people who don’t know much about education, but inexplicably think their opinion has some value anyway”?

I’ll show you impact

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.

The thrill of the audience response

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.

I love the smell of traffic in the evening

See those blue bars in the photo above? That’s you, that is.

Huge thanks to everyone who’s tweeted, said something positive on Facebook, posted to Boing Boing, whatever – yesterday was this site’s busiest day to date by a factor of five. Then today’s hit twice yesterday’s page views. Amazing, not to mention gratifying, but traffic is nothing compared to all your positive comments.

This site is itself an experiment, trying to plug a gap we’ve been worrying about for years. It looks like we’ve struck a chord. Fantastic, and thank you.

If you’re a teacher in the UK: join Demo Day 2014. Take the pledge to perform a demonstration for your students, on 20th March. It doesn’t have to be one of the demos featured here, the choice is up to you. But take the pledge, and spread the word:

Get Set… Demonstrate, at the British Science Association.

We’ve another of our demo films each day this week (and on Monday – bonus!), and we’ll keep the site ticking over until the grand premier of our epic Demo documentary film. Early March for that, maybe?

Meanwhile, it looks like Alom and I are making three more films of biology practicals in the near future. Who’s next? Is it time for some maths, or computer science? Or would the physicists get jealous?

Flame colours

A scary article in the NY Times last Friday about a chemistry demo they refer to as “the rainbow”:

“With about 30 students watching from their desks, a snakelike flame tore through the air, missing the students closest to the teacher’s desk, but enveloping Alonzo Yanes, 16, searing and melting the skin on his face and body, according to witnesses. He was in critical condition on Friday[…]”

Just weeks ago, the article relates, the demo was the focus of a safety bulletin from the US Chemical Safety Board, and this film:

Here in the UK, I think we’d more commonly refer to the demo as “Flame colours”, and at the head of this post is a photo I took of it a few years ago. As best I can tell, the cause of the accidents in the US has been demonstrators topping up the flame straight from the methanol bottle, leading to the ignition of a large volume of fuel vapour.

Now, I’d hope most people reading this blog will be wincing right now. It was drilled into us (in school) that you never open a bottle of fuel near a naked flame, and that the correct procedure here is to ensure the watch glasses are cold before adding a small amount of fuel (typically with a pipette), then sealing the fuel bottle and removing it to a safe distance, before lighting the mixture in the watch glasses.

That would be standard lab practice, and it’s near-inconceivable that a teacher would pour meths from a bottle directly onto a flame. However, one thing we learned from SciCast is that we’re into the second generation of science teachers who’ve never really ‘done’ practical science. Recent science graduates don’t necessarily know how to handle flammable materials; they may never have been taught.

That generational knowledge gap was one impetus behind the demonstration films Alom and I have been making for the National STEM Centre and others, and also for this website. So pass this on, please, and let’s not make assumptions.

Oh, and if you’re a teacher in the UK, the version of this demo you should do is probably the one with ethanol spray bottles. That’s the version the Royal Society of Chemistry and Nuffield promote, but – as ever – check with CLEAPSS for their standing advice.

[EDIT 9/1/2014 – The RSC’s Education in Chemistry blog has picked up the story. Their post includes a quote from Steve Jones, Director of CLEAPSS.]

[EDIT 2 15/1/2014 – I somehow missed the NY Times’ follow-up story about the school involved in the incident above being inspected by the Fire Department, and being given notices to improve on a range of issues. Also, for the UK audience I should note that the Scottish equivalent of CLEAPSS is SSERC.]