Knowledge vs Understanding

Subject knowledge has enjoyed a recent rehabilitation within education. Whilst there are groups ideologically opposed to teaching content (either on the grounds that it ‘stifles creativity’ or amounts to ‘indoctrination’), the simple fact that children and schools are typically assessed using external exams which test subject knowledge means that developing effective ways of teach knowledge will be important for the foreseeable future.

Furthermore, knowledge is not a limiting factor on our wider ambitions for students. I want mine to reason critically, understand and apply complex ideas. I need them to evaluate theories whilst avoiding over-reliance on straw-men, over-simplification of the debate, or glib dismissal of evidence. The foundation stone for these higher-order ‘skills’ is their knowledge of the subject.

However, there was an interesting discussion on twitter about whether knowledge was both necessary and sufficient for understanding. It’s an interesting question – given the evidence that teaching knowledge is so important – so I set myself the task of trying to generate some counter-examples.

Is knowledge sufficient for understanding?

My argument would be that it is not.

Psychologists from Piaget to Sweller couch learning in terms of the acquisition and refinement of schema. One of the limitations, I hypothesise, of direct instruction techniques is the fact that students do not come to us ‘tabula rasa’ – rather they come with many preconceptions already in place. These preconceptions – Geary dubs them ‘folk physics’ or ‘folk biology’, etc – are sometimes extraordinarily difficult to change; even after the scientific knowledge has been taught and recalled successfully under exam conditions.

A classic example of this comes from Taber’s work on chemical misconceptions for the Royal Society of Chemistry (Source: H.-D. Barke et al., Misconceptions in Chemistry) :

“When people are given a piece of wood and asked how the material got into the tree they commonly reply that most of it came from the soil’’. Even though, in biology, the subject of photosynthesis is taught with the use of carbon dioxide, water, light and heat for the synthesis of sugar and starch, still many students when asked where wood comes from, reply: ‘‘from the soil’’. Most students seem to have their knowledge of biology lectures in special ‘‘compartments’’ of their brain. They do not link them to their every-day life understanding: ‘‘Presumably most of the graduates would have been able to explain the basics of photosynthesis (had that been the question), but perhaps they had stored their learning about the scientific process (where carbon in the tree originates from gaseous carbon dioxide in the air) in a different compartment from their ‘everyday knowledge’ that plants get their nutrition from the soil”

This has been my experience as a science teacher. KS3 pupils who could explain photosynthesis to me, write a word equation and sometimes even balance up the chemical formula equation – would quite happily say ‘the soil’ when asked where the ‘wood of a tree’ comes from. Indeed, I’ve used this question in CPD sessions and some teachers give that answer too …

This is just one example – but the Misconceptions in Chemistry article has lots more – but I think it’s a case of where effective transmission of subject knowledge alone does not necessarily lead to scientifically accurate understanding. Now – misconceptions aren’t the be-all-and-end-all, but how well different instructional techniques correct misconceptions, I suggest, represents an important test of efficacy.

Can you have understanding without knowledge?

Again, I think possibly yes (in a highly limited sense).

A powerful tool in science teaching is the use of analogy. One of the benefits of analogies is that it allows the expression of concepts in the absence of the complex subject knowledge that would ordinarily allow you to derive the same understanding.

I posted an example recently – using a motorway analogy to teach the behaviour of current and voltage in circuits. The analogy takes away some of the (often confusing for novice learners) knowledge components (e.g. what are Coulombs and how energy is transferred by the movement of electrical charge) and provides a simplified conceptual model so that students can reason about the behaviour of the circuit without getting hung up on the complexities of Kirchhoff’s law. Analogies are an effective way to teach science – possibly because they reduce the cognitive load when teaching a difficult concept.

Whilst eventually students will need to tackle the specifics of that subject knowledge – using analogies allows Y7s to get to quickly get to grips with the basics of circuit behaviour. Pupils recognise that there aren’t really cars (or coal trucks) zooming around a motorway, or thieves stealing petrol, but the concrete objects involved help them more quickly accommodate the new (and sometimes counter-intuitive) ideas involved.

Conclusion

We need to consider knowledge and conceptual understanding when evaluating instructional techniques. The efficacy of different instructional techniques in successfully challenging misconceptions would be an interesting RCT (*if any readers know one – please contact me!). However, the persistence of misconceptions and the success of teaching through analogies might imply that conceptual understanding can sometimes be more than the sum of the content knowledge involved.

I will say though, that discovery learning techniques appear to fare somewhat worse when it comes to teaching concepts and challenging misconceptions (e.g. Kirschner). At an anecdotal level, I’ve had Y7s merrily come up to me at the end of a ‘discovery’ practical on electrical circuits and report that adding a bulb in a parallel circuit made both bulbs go dim – because that’s what they expected should be the right answer – so they ‘corrected’ the result!

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