How We Learn Concepts in Science

In my last flurry of blogs (here, here and here), I wrote about the limits of definitions for learning . Learning the definition does incredibly little to develop understanding. For example: Electrical current is the rate of flow of charge.

Even if you know what rate means and you have a clear understanding of charge, you still don’t really know what current is. You don’t know how to use it in calculations or how to use it in writing or discussion. You don’t have a proper ‘feel’ for current.


Thomas Kuhn, the philosopher of science, argues that we learn scientific concepts by ‘acquiring an arsenal of exemplars‘ – often the bank of questions at the end of each chapter in textbooks (Kuhn, second thoughts on paradigms, 1977).

So spending learning time to memorising  the definition is not a great use of time. Spend that time on learning exemplars instead. One effective way of doing this is by using worked examples. Hattie (in Visible Learning, 2009, p172/3) describes the worked example cycle as typically:

  1. exposure to the example question
  2. a training phase
  3. a testing phase.

Variations include: matching text to diagrams; fading (gradually removing steps in the example) and self-explanation of the stages.

In addition to learning to solve the exemplar questions, I would add: talk about models and practical work and reading and writing sentences containing the target concepts.

This leades to a far richer undrestanding of a concept – I know my definitions now, though I didn’t when I was using them as part of my degree. I didn’t need to know them – I understood them instead.


Electricity’s Colourful Past

Yesterday I wrote about electric charge and its confusing meanings (here). I had intended to write about voltage and current today, but after a discussion with Mary Whitehouse @MaryUYSEG and a troubled night’s sleep, I’ve decided to write about the word electricity instead. Much of the information in this blog is taken from Iwan Rhys Morus’s (@irmorus1) brilliant book: Shocking Bodies.

Among physicists, the word electricity has lost it’s usefulness. Instead, it is rather a nuisance: an idea with a colourful past. But that past is glorious.

Electricity’s colourful past

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Electric Charge – why it is difficult to understand and how to help.

My heart has never been in definitions. It was set against them in Africa 20 years ago, when I was teaching physics in Ghana. The exams, and the students, prioritised the recall of definitions. And I didn’t know them – I just converted the equation into words (I=Q/t Definition: current is the rate of flow of charge). 

When my definitions disagreed with the examboard’s definition, I saw doubt, fear and sometimes anger on the faces of my students. So I learnt the exam board’s definitions, sadly, not with good grace.

Recently, I have begun thinking about definitions again. I often see teachers asking students to write their own definitions as either a warm-up or assessments task. But I think this is too hard. If you want students to learn a definition, learn the exam board one.

But definitions are not the key to understanding a concept. Daisy Christodoulou’s new book (Making Good Progress) quotes Thomas Kuhn when talking about definitions. She (and he) make the point that a definition doesn’t lead to understanding: repeated exposure to the concept through discussion, models and texts; solving the discipline’s standard questions about the concept and carring out the standard practicals leads the learner to a rich understanding. Then the definition becomes useful. Continue reading


Using Comparative Judgement to Rank the Importance of Concepts

If you haven’t heard of comparative judgement (CJ), it is the latest fashionable way for judging the quality of student work (see here and here) – although it’s not really new. I think it has great potential for judging longer written answers (or even short answers) beyond just right and wrong – some right answers (and some wrong answers) are better than others and this should be recognised and explored.

I had the idea of trying our CJ by ranking energy statements into order of importance for understanding energy. I took the statements from the ASEs Big Ideas in Science energy section here.

10 physics teachers ranked the statements using the CJ engine at Making 25 comparisons (each comparison taking, on average, less than 10s), the correlation was surprisingly high (0.82). The top 5 are:

  1. When energy is transferred from one object to others the total amount of energy in the universe remains the same; the amount that one object loses is the same as the other objects gain.
  2. Energy cannot be created or destroyed.
  3. Objects can have stored energy (that is, the ability to make things change) either because of their chemical composition (as in fuels and batteries), their movement, their temperature, their position in a gravitational or other field, or because of compression or distortion of an elastic material.
  4. An object at a higher temperature heats the surroundings or cooler objects in contact with it until they are all at the same temperature.”
  5. The transfer of energy in making things happen almost always results in some energy being shared more widely, heating more atoms and molecules and spreading out by conduction or radiation.

The full bank of statements, ranked, is here.

I’d be really interested if anyone has tried this with written exam answers.


core knowledge, deep reading, history of science, Literacy, reading, science, teaching

Science: A Great Source of Metaphor…

Have you got time to read two very short science texts? Both of them are surprising and wonderful.

First text: a beautiful piece of writing by Lewis Thomas called ‘The Lives of A Cell’ (thelivesofacell)   – you will thank me for this.

Second text: the original paper by Crick and Watson (watsoncrick) announcing the structure of DNA (it’s 1 side of A4 and it is readable – just read it).

Crick and Watson – DNA model

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A Little Knowledge is a Many-Splendored Thing

We’ve been thinking about knowledge and reading a lot recently. Christine Counsell has given the leaders of my trust reading homework. Chapter 2 of Hirsch’s On Cultural Literacy has some penny-dropping lines. My favourite is: Our cognitive life takes place through a small window of attention that is framed by short-term memory. Yes it does.

One of the key points in the chapter is the impact of prior knowledge on that window of attention and on children’s ability to comprehend texts. My colleagues and I have been discussing this for some time. We’ve been dissatisfied with our current literacy course and how it does little to develop knowledge and vocabulary. It occurred to two of us simultaneously that our pupils already have a bank of stored experience and knowledge, but that we have left it to lie dormant: topic work.

In common with most primary schools, we teach science, art and the humanities through topic work. Each topic (Romans, Victorians, creatures of the deep, etc.) begins with a stimulus, a trip or activity, which leads to a piece of writing each week. For our children, this has been distinct from reading.

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