Teaching in the black box

Tyndall's lecture

"No...it's 'wingardium levi-OH-sa'," a lone voice in the audience cried.

I remembered using biuret solution in my old biochemistry classes at university, many moons ago. It’s a pale smurf-blue liquid that darkens in the presence of protein. Along with benedict’s test and the primary school favourite of iodine-on-starch, classroom food chemistry commonly relies on such demonstrations to provide students with the practical means to analyse unidentified substances.

As a teacher, I found using solutions like biuret reagent introduced a tiny dilemma. While I was pleased that students were engaged in problem solving, this liquid was simply a magical device for enchanting an answer from a recipe. I found similar problems in teaching mathematics – whatever came out of the small black box on their desk was the solution. So what if the calculator said the ant was a metre long? Who cares if the solution turned purple in the presence of sugar? That’s the answer that the black box produced, reality be damned!

Recently I discovered I could make biuret solution from material bought at the hardware. Drain cleaner and garden variety ‘bluestone’ (copper sulphate crystals) to be exact. Add some protein powder and watch that baby turn purple. Best of all, the materials aren’t commonly associated with lab coats and Erlenmeyer flasks.

I’ve found over years of making and finding science demonstrations that science works best as a process of connections. No child is familiar with biuret reagent. Many have come across sodium hydroxide in the form of Draino, or copper sulphate pentahydrate as a soil additive. From familiarity connections can be built far more easily than mysterious tinctures. Suddenly science is embedded in the real world of hardware stores and garden centres, leaving Hogwarts far behind.

So-called ‘black box’ science is all too common in education. Input goes in one end of the box and output comes out the other side. In between is all polyjuice and Quidditch. I still cringe at any science show that attempts to excite children by demonstrating a chemical reaction by referring to the reagents as ‘potions’.

The demonstration has a long, proud history in science communication. Sir Humphry Davy and his successor, Michael Faraday, were well known for their spectacular lectures. Every baby boomer in Australia knows ‘why it is so’ when an egg is sucked into a bottle. ‘Don’t tell, show!’ is almost second nature in science education. And for good reason. When it comes to constructing knowledge, our brains have a bias for personal experience.

Yet in communication, this can be a double edged sword. The surrounding context for such experiences carries tremendous weight when successfully incorporating an idea into a mental model.

A classic example is the observation of a saucer of water water rising into a glass inverted over a lit candle. Many a child has gone away believing they just saw air disappear as it was burned by a flame, creating a vacuum. The reasons for this misinterpretation are numerous; maybe their prior knowledge led them to assume matter can disappear. Or their teacher provided them with a poor metaphor. Perhaps there were other demonstrations they’d recently engaged in that created confusion about the underlying physics. The teacher simply could have provided incorrect information.

In any case, that same potency behind the demonstration that was of such benefit can prove to be the source of misinformation if used without due thought given to the culture of the audience, or if its execution goes awry. As every magician knows, it’s not just the slight of hand that deceives an audience, but your story entangled with their expectations. Magicians who fumble their narrative or fail to understand their audience can be as nimble as they like – the rabbit will still be obvious in the hat.

It still shocks me when I come across science presenters or teachers who confess to not having tested a demonstration before going ‘live’, or use metaphors that are even more complicated than the phenomenon they’re explaining. Often a presenter or educator will attempt to go for flash and entertainment at the expense of audience connection, compromising on tight similes by investing in drama, noise and pyrotechnics.

Having now personally found, created or modified over 150 science demonstrations (one a week for the past three years, more or less) from simple materials, I’ve learned a couple of things. One is to always do a trial run. Two, never underestimate what your audience might find interesting. And three, know the limits of what is being observed. Lest your audience walk away with fantasies of one mile long ants and polyjuice potions instead of an appreciation of how useful science really is at explaining what we see.

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Published in: on February 11, 2011 at 3:14 pm  Comments (1)  
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  1. […] McRae has a nice piece on ‘teaching in the black box‘; where A leads to C via B, with B obscured from inquiry thanks to the use of recipe-like […]


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