Science: The art of explanation

23 Jun

 

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Science is nothing without communication; science is about making observations and explaining them. So why do some scientists become TV stars, adored even by those who “don’t get science?“. My opinion is that along with an obvious passion for their subject they also are great communicators; they explain the science stuff well. The greats, such as David Attenborough, Brian Cox and the geeky, yet sexy, presenters of ‘Bang goes the theory’ have nailed it. They have made science accessible, interesting and fun because the average person on the street can understand most, if not all of what they are saying. We, as teachers, need to aim to communicate like this and, more importantly, teach our future scientists to do it too.

Science teachers, like all their colleagues, have their own way of explaining certain concepts or processes. Some teachers are brilliant at this and you find yourself regularly asking them for ideas on how to explain topics to Year 10.  I know there are certain parts of the syllabus that I look forward to teaching because they are tricky and I’ll get satisfaction from seeing the kids understand those topics due to my own special way of explaining it. This is one of those, ”I am an expert, I shall explain this to you and you will be amazed and eternally in awe of me” moments that I need to use sparingly. A better approach is to encourage students to develop their own explanations, models and analogies and then evaluate their relative strengths and weaknesses. I wish I’d kept a record of all the different ideas my students have come up with for explaining or modelling a scientific concept. My slant is usually if it’s a bit quirky, it’s far more likely to stick! I definitely recommend science departments compiling a shared list of ”effective ways to explain concepts”.

Models & Analogies

Science teachers use models and analogies regularly to assist with explanations. The Key Stage 3 strategy materials (links below) are definitely worth revisiting to reflect on the use of these tools in the classroom. I have selected some of my most commonly used models/analogies for a brief discussion:

Particles

Particles are such an abstract idea that I always get the molymods out as early as possible. My way around the scary technician who only wants them used for A level is to make up small packs for Key Stage 3 in resealable plastic bags with a little checklist of exactly the pieces that must be in the pack at the end (generally enough parts to show methane and oxygen (x2) converting to carbon dioxide and water). An alternative would be the little fluffy pom-poms you will find in the craft section of the supermarket.

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Osmosis

Ask any adult and they probably remember memorising the definition but have absolutely no idea what it actually means in practice! Students have to see it in action, so I set them the homework of taking two slices of cucumber (or potato/peeled grapes) and putting one into a cup of tap water and the other into a cup of very salty water. They then try to explain their findings before and after learning about osmosis. There are many great animations of the process of osmosis but if students physically make their own model showing the different sized particles and the membrane (and possibly make their own mini animations using them) the level of understanding is deepened.

Electrical Circuits

Oh dear, I need a physics example. One of the best example as a non-specialist I have used is from the ASE book ‘The adventures of Charlie the coulomb’ to explain many features of electrical circuits. (http://old.ase.org.uk/htm/book_store/detail.php?SIID=86)  It allows progression from Key Stage 3 to 4 by introducing current, potential difference and resistance.

National Strategy materials on using models and analogies: http://www.nationalstemcentre.org.uk/elibrary/resource/5326/misconceptions-in-key-stage-three-science-training-materials

http://www.nationalstemcentre.org.uk/elibrary/resource/7416/using-models

http://www.nationalstemcentre.org.uk/elibrary/resource/5305/strengthening-teaching-and-learning-in-science-through-using-different-pedagogies

Starting points for explanations

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How do I encourage students to explain what they are seeing?

I generally start by showing them something that will spark their interest so that they are eager to explain it. These are some of my favourites:

  1. The ‘fingerboiler pen’ (http://www.4physics.com/catalog/product_info.php/products_id/234) ,
  2. The ‘passion meter’ (a round bottom flask with a bung and capillary tube in the top – a student is asked to hold the flask around the bottom under water in a glass trough. The more it bubbles, the ‘fitter’ or more passionate the person is. You control this because if you cool the flask first under a tap, it will bubble furiously but if you pre-warm it by holding it yourself, it won’t bubble at all!)
  3. The amazing floating globe (http://www.youtube.com/watch?v=xnNI4aw9Da0)
  4. The Hoffman voltameter splitting water (http://en.wikipedia.org/wiki/Hofmann_voltameter)
  5. The burning money trick (http://chemistry.about.com/od/demonstrationsexperiments/ss/burnmoney.htm)

These lessons are always focused on observing and discussing ideas for explanations before trying to write something individually. One of the most memorable science lessons I have seen was a year 8 lesson about thermal insulation. As students entered the laboratory they were given an ice cube and the instructions to preserve it for as long as possible. One student immediately put the ice cube under the cold tap, another left it on the desk whilst another wrapped it in their blazer. The students were asked to justify their tactic and explain the findings of the class.

My favourite explanation still has to be the reactivity series explained using students who are going out with each other. This obviously works best if there is a back story and you can exploit this, but the general idea is that you represent the non-metal as a girl in the class and the metal as a boy and ask them to stand at the front of the class linking arms. They are now ‘bonded’ or going out. The more reactive metal will be represented by another boy in the class – you may decide to go for a bigger, beefier young man or one who is a bit feisty to be more reactive, or go for one who is comically tiny in comparison with the first boy. Either way, the more reactive metal has to gently nudge the other boy out of the way and take his place attached to the young lady.

 

Writing (and not writing) explanations

In order to develop written explanations, I have used the following ‘thinking frame’ template in many different ways. I believe it originated from the Cams Hill Science consortium and was picked up by the Science National strategies to be included in their Key Stage 3 key ideas materials. It enables students to develop their explanations by first considering the key terms and diagrams (such as particle diagrams or chemical equations), then putting those ideas into bullet points before finally writing a full paragraph. These paragraphs work particularly well with ABC peer critique (outlined below).

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Although we want students to be able to write clear paragraphs to explain scientific processes and concepts, explanations are really just about demonstrating your understanding.  In order to mix things up a little, rather than always expecting a written paragraph, I often ask students to explain using diagrams ‘explain the process of digestion using a cartoon strip’, models, flow charts or just the fewest words possible.

My final ideas are used across many subjects in many different ways but I still often forget how much fun explanations can be when students are asked to explain for a particular audience. Those that spring to mind are ”explain the difference between global warming, the greenhouse effect and climate change to my gran”, ”explain elements, mixtures and compounds to a six year old” and ”explain the process of peer review to Jay Z.“

Explanations are key to understanding science. It is important to judge your audience before explaining anything. In particular, what prior knowledge, attitude and experiences do they have which will influence how they make sense of the explanation? Both teachers and students should consider this when explaining a subject to their particular audience.  I try to use practical examples or familiar scenarios as often as possible and vary the explanation techniques to ensure lessons are as accessible and interesting as possible.

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