Thought Depends on Knowledge

Guest Blog by David Didau

Recently Paul went to Making Shift Happen 2017, a happening in Amsterdam where the keynotes were Anders Ericsson, Stellan Ohlsson, Yana Weinstein, David Didau, and Lucy Crehan. He asked David and Yana to please write a guest blog for us. Here is David’s blog!

Two children start school on the same day, mid-way through the academic year. Their new teacher knows nothing about their prior attainment so decides to give them a reading assessment to get a sense of their abilities.

Sophie loves reading. Her parents read to her endlessly in the first few years of her life and, at her previous school, she quickly mastered phonics (i.e., can identify sounds in words and sentences) and rapidly moved to reading stories. As a result she has a wide vocabulary and surprisingly precocious knowledge of words.

Jarred hates reading. There were no books in the home he grew up in and, when he started school he was suffering with undiagnosed glue ear. He wasn’t able to clearly hear the distinctions between vowel and consonant sounds and he struggled to pick up what all the other children seemed to find easy. His teacher assumed he was a little slow and gave him pictures books to look at. He likes picture books because they don’t tend to have much writing in them. As a result, he has a limited vocabulary and knows very little of the world outside of his immediate experiences.

Both children sit the reading assessment. Sophie does well, Jarred does not. Their teacher puts Sophie with the other ‘able’ children so they can stretch each other further. She’s given more challenging content and her group is encouraged to plough through lessons as quickly as they’re able. Jarred is seated on a table with the other children who are struggling. He’s given less challenging activities and is helped through the material at a slower pace.

Whenever we assess two children, the one who knows most about the topic at hand will outperform the one who knows less, whatever their innate abilities. Although it’s of course true that different children have different capacities, it’s trivially true. What really matters is quality and quantity of what they know.

Depending on what it is we’ve assessed, we might conclude that one child is more able than another and start treating her or him differently, thereby creating a self-fulfilling prophecy. But, if the initial difference in performance is caused by one child simply possessing more knowledge than the other, it should be obvious that a different solution is warranted. How will these children ever catch up by going slower and learning less?


Knowledge is often conceived of as factual information lying inert in our brains, just waiting to be retrieved and put to use. It’s little wonder that those who think this way see teaching children facts as worthless in the information age. Whenever we need to know an item of information we can look it up quickly and reliably on the Internet. Or can you?

This view of knowledge is unhelpful. Instead we should view it as an organised and interconnected web of information; the stuff not just that we think about but what we think with. We’re unaware of much – perhaps most – of what we know. Contrary to our intuitions, we have no memory of memorising much of what we know. Skills such as reading – or driving – actually consist of many thousands or particles of information that we at some point committed to memory. Few skilled readers, for instance, are aware of having memorised the 44 phonemes of the English language and the 170+ graphemes we use to represent them in writing. Yet had we not committed them to memory, reading would be impossible.


This sort of procedural knowledge becomes increasingly effortless to use the better we know it. If we know it well enough, we automatise the procedures we want to learn and as they become automatic, we stop thinking about them, giving us greater capacity to think about other, more interesting things. Quite literally, the better we know some things, the less we’re aware of what it is we know.

Of course there are many things stored in our memory that we know we know. We’re able to declare that Paris is the capital city of France and that a mile is roughly 1.6 kilometres in length. But this kind of factual declarative knowledge is just the tip of a vast iceberg. The increasingly invisible nature of what we know allows otherwise intelligent people to go around spouting that they learned nothing at school and everything they know and can do they have taught themselves. Just because we don’t remember where or how we learned a thing doesn’t mean we don’t know it. Although some of our memories are episodic (i.e., the collection of past personal experiences that occurred at a particular time and place) and allow us to relive events from our past in vivid detail, much of what we remember is semantic information – underlying concepts and ideas that allow us to process new information.

The pleas for schools to teach so-called ‘21st century skills’ are rooted in the mistaken belief that being taught how to solve generic problems or how to think critically in a range of contexts will make children better suited to the uncertainties of modern life. On the contrary, such efforts merely advantage the most advantaged and condemn the disadvantaged to lag ever further behind. This is known as the Matthew Effect. The more we know, the better we can think. If you know nothing about a subject then, quite literally, you cannot think about it. Try imagining something entirely unrelated to anything you have ever encountered. All you can do is think about things you have some awareness of and try to imagine how they might be altered. If you know little about a subject it’s very difficult if not impossible to think about it for long or in more depth. We quickly tire exploring our ignorance. But when we know something well, we can start thinking about how it’s composed, how it related to other things we know, and why it has the characteristics we observe. This depends on knowledge.

If we’re really interested in preparing young people for an uncertain future our best bet might be to ensure they know as much as possible. We should, perhaps, prioritise those things that allow them to make the most useful connections and share in the most interesting discussions. Some things are like intellectual Velcro; the stuff of school sticks to them must better than to other, less useful types of knowledge. My advice is to focus on getting children to automatise the most useful procedural knowledge (phoneme/grapheme relationships, number facts, a basic chronological sequence of world history and geographic knowledge) and then concentrate on giving them access to the most powerful and culturally rich curriculum content possible so that they can critique, argue about, explore and add to the store of human cultural achievement.


After teaching for 15 years, David Didau is now a freelance writer, speaker and trainer. He also teaches English Studies as part of the BPP University PGCE course. His blog, The Learning Spy, is one of the most influential education blogs in the UK and has won a number of awards. In addition he has also authored a number of books including ‘The Secret of Literacy’ and ‘What if everything you knew about education was wrong?’. His latest book, ‘What Every Teacher Needs To Know About Psychology is a practical guide for teachers to understand and implement the most important principles from psychology in their teaching.

You can find him on Twitter as @David Didau.

…and this is his blog The Learning Spy:



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