Science nuggets

23 03 2016

My three evaluation questions are What’s the Story? Who’s the Audience? and Where’s the science?

Today I’d like to think a little about the third question. 

Every science demo we perform relies on or reveals an essential nugget (for want of a better term) of science. The way we explain that nugget of science depends on our Audience and the Story we have chosen to tell. Nevertheless each demo is still underpinned by a nugget of science and if we fail to get that across we might as well not bother with anything else. 

Take this classic demo.

You probably know what’s going to happen. The little ball is going to rocket up off bigger ball. It’s a spectacular self-working demo that requires cheap non-specialist equipment. No wonder it is such a popular choice for presenters. 

The demo is comprehensively described on the page where I took that picture from. What is the nugget of science in this demo?

Most times I see this performed the balls are dropped, the little ball shoots off, we are asked to marvel at what happened, often we are shown it happen again, then it is explained. 

But what’s the nugget?

It doesn’t matter who your Audience is or what your Story the nugget here is that 

the basketball doesn’t bounce as high with the tennis ball on top

If your presentation of this demo doesn’t get across this simple point that the basketball will bounce to one height by itself but a lower height with the tennis ball on top then you’ve missed the nugget. 

All the talk of conservation of energy and transfer of momentum will mean nothing if the different bounce heights haven’t been noticed. 

Once you’ve identified the nugget then then the best presentation of the demo should be clear. In this demo we need to show the balls dropped separately then together. 

This video does a very good job of explaining it. 

It should be clear from watching this video that explaining this demo takes time and you can cover many science topics with it. What they do well is show the nugget: the basketball doesn’t bounce as high with the tennis ball on top.  

This video gives another example to stress the point. Someone double bouncing someone on a trampoline will send the other person higher but they won’t go as high. 

We must search for the nugget in every demo we perform. Every demo has one single piece of scientific information in it that, however we choose to present it, must be got across. 

I’ve just had the pleasure of spending a week working with liquid nitrogen. The context for the show was space and I was able to use the LN2 to demonstrate alien atmospheres, the formation of clouds, changes of state, reversible and irreversible reactions, fractional distillation and water content in living cells but I was careful to not lose sight of LN2’s science nugget:

liquid nitrogen is the coldest substance you will ever encounter

If you are working with LN2 and your audience hasn’t grasped that liquid nitrogen is unbelievably cold then whatever else you’ve tried to get across won’t have been properly understood. 

I know reading this that probably sounds obvious to you. If you’ve managed to get your hands on a dewar of LN2 then your training will have stressed the extreme cold to you. Remember though the audience might not have seen LN2 before and even if they have it was probably at another science event where it’s properties might not have been properly explained. 

Just as with the ball on ball demo height difference you must cover the extreme cold of the LN2. How do you know if you’ve covered the nugget? Ask your audience. 

If I was being honest I’d say more than half, maybe even three quarters of the LN2 demos I’ve watched over the years haven’t stressed the extreme cold enough that the audience has grasped it. I always get someone in the audience of a LN2 show I’ve watched to tell me something about the LN2? Too often, even after prompting, they can’t tell me that it is incredibly cold. If someone in the audience of a show I’ve done can’t tell me I immediately review how I’ve explained it. 

Take the fizzy tablet dropped into a film canister demo. Here’s the wonderful Steve Spangler performing this demo. What’s the nugget?

Here the nugget is when the tablets get wet they fizz. He demonstrates this simply by putting a couple of tablets in a glass of water. 

It is too easy to assume that your audience will know what an Alca Seltzer tablet does and forget to stress this nugget. If you don’t show the tablets fizzing then everything that follows might be misunderstood. 

What you then do with the nugget is up to you. Acid plus base reactions, build up of pressure, solids and liquids taking up less space than gases, compressibility of gases, friction and seals can a be discussed but just as with the LN2 and the balls if you’ve not covered the nugget you’ve massively reduced your chances of your audience understanding anything of what you are doing. 

the basketball doesn’t bounce as high… the LN2 is extremely cold… the tablets will fizz when they get wet

Find your nuggets in all your demos. Take the time to cover them clearly. Only then go on to show or explain what you’d planned. 

There’s one more excellent example at the start of the Steve Spangler clip. He demonstrates the cornflour on a speaker. 

What’s the nugget with the speaker demo? The speaker is vibrating

Steve takes the time to show this using some ping pong balls. That bounce out of the speaker. 

It’s such an obvious and simple thing to show but in all the times you’ve seen this demo being performed ask yourself how many times have you seen a presenter take the time to show this absolutely vital piece of information? 



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