Improving teaching and learning with the Bayesian method


Matt Bromley does not know the secret to developing outstanding teaching and learning, but the story of the hunt for a lost American submarine in 1968 could hold the key. He introduces the brilliant simplicity of the Bayesian Method.


On June 5, 1968, an American submarine called the USS Scorpion was declared lost and its 99 crewman presumed dead. An immediate search was initiated but without success because – with a potential search area stretching out thousands of square miles – it was quite simply like finding a needle in a haystack. 

Accordingly, the USS Scorpion was struck from the Naval Vessel Register on June 30. 

Later that year, however, another search led by Dr John Craven – the chief scientist of the US Navy’s Special Projects Division – employed rather different methods to try and find the vessel.

Dr Craven polled a wide array of specialists in various fields for their thoughts of where the submarine might be. Their guesses were then pooled into a single average guess. 

This method draws on the Bayesian theory, which was first deployed during the search for a hydrogen bomb lost off the coast of Palomares, Spain, in January 1966.

Not one of the experts’ guesses was right. But the average of all their guesses was surprisingly accurate and led the recovery team to within just 183 metres of the lost submarine – in 3,000 metres of water about 740 kilometres south west of the Azores Islands.

I believe in the Bayesian method of improving teaching and learning...

Better together

I have been a teacher for longer than I would care to admit and I have worked as a school leader, teacher-trainer, lecturer and consultant headteacher. I have recently been appointed director of teaching and learning for a large education trust. And yet – let me whisper this – I have a confession to make: I do not possess a panacea, I do not have an elixir, a pill which once popped will proffer outstanding teaching and learning every time. 

And nor should I

To paraphrase Sir Tim Brighouse – former chief advisor to London Schools – it is not my job to provide all the right answers; it is my job to ask all the right questions. 

I do not expect any one of my 1,500 new colleagues to know the secret to outstanding teaching and learning either. I imagine we will all have our own thoughts about what works and what does not – and about what great teaching is and is not – but no single opinion will take our schools and colleges to within 200 yards of “outstanding”. 

However – like Dr Craven’s team of experts – together, we will find all the answers and we will provide consistently outstanding teaching and learning in every corner of our organisation. 

In short – and let this be my motto – we are better together.

And why is it important that we ensure the quality of teaching is the best it can be? Because teachers make a big difference.

Hanushek and Rivkin (2006) say that if we take a group of 50 teachers, the students taught by the most effective teacher in that group will learn in six months what those taught by the average teacher will learn in a year. 

And, more damningly, students taught by the least effective teacher in that group of 50 will take two years to achieve the same amount of learning.

Furthermore, according to Hamre and Pianta (2005), in the classrooms of the most effective teachers, students from disadvantaged backgrounds learn at the same rate as those from advantaged backgrounds. 

The art of being wise

The 19th century philosopher William James once said that “the art of being wise is knowing what to overlook” and I believe – in improving teaching and learning – we should do just this. To put it less eloquently, the main thing is to keep the main thing the main thing.

In other words, we should focus on the most important aspects of teaching and learning – the real drivers of change – and take small but sustainable steps forward. 

We should not adopt a different focus each week, whereby one initiative erases all memory of the last. Nor should we employ a “one-size-fits-all” approach which assumes that all areas of our schools and colleges share the same strengths and weaknesses. No. We should ensure a personalised, common-sense approach to improvement planning.

Economists have an 80/20 rule which they call “the law of the vital few”. It is also known as the Pareto Principle – named after the Italian economist Vilfredo Pareto, who observed in 1906 that 80 per cent of the land in Italy was owned by 20 per cent of the population. 

Joseph Juran developed the principle by observing that 20 per cent of the pea-pods in his garden contained 80 per cent of the peas. From this, we get the popular belief that 80 per cent of the effects come from 20 per cent of the causes. In business, for example, it is believed that 80 per cent of sales come from 20 per cent of customers.

It follows, therefore, that to become outstanding we should focus on improving the 20 per cent of things that create the most value. We will get stronger results if we spend our time practising the most important things. 

And even if we already do the most important things well, there is real value in practising them further. The value of practice increases once the thing being practised has been mastered. 

Doug Lemov in his book Practice Perfect says that to keep practising something once we have already mastered it is to develop automaticity, fluidity, and creativity. 

To put it another way, if you are already teaching outstanding lessons time after time, then the last thing you should do is become complacent; instead, you should keep practising and you should seek to share your expertise with colleagues.

I believe we should focus on the 20 per cent of things that yield 80 per cent of the improvements.

There is another advantage of focusing on the main thing, as Professor Ben Levin, the former deputy director of education in Ontario, says: “Having a great new idea is less important to success than getting ordinary things done correctly and efficiently.” 

And the “ordinary thing” has to be what works in the classroom because, as Professors Paul Black and Dylan Wiliam say in Inside the Black Box: “Standards are raised only by changes which are put into direct effect by teachers and pupils in classrooms.”

Evidence-based practice

In deciding what the “main thing” is, I believe we should use evidence-based practice. For example, we should look to quality external evidence such as Professor John Hattie’s book Visible Learning and in the Educational Endowment Foundation’s (EEF) Pupil Premium Toolkit, and Prof Wiliam’s work on Assessment for Learning.

You see, I am certain – by way of example – that within the key 20 per cent of drivers is feedback. Both Prof Hattie and the EEF rank the quality of feedback as the number one classroom intervention. In other words, their research suggests that improving feedback will have the greatest impact on student learning and progress, far greater impact, say, than reducing class sizes. The Sutton Trust says that improving feedback adds eight months of extra learning while Prof Hattie says it has an effect size of 0.73. 

The teaching and learning brigade

And how should we lead the charge on feedback and the other key drivers? Through quality, staff-driven, collaborative professional development – CPD which is sustained over the long-term, which is focused on students’ learning, and which is continually and formatively evaluated. 

Professor Judith Little, an American educational researcher who works at the University of Berkeley in California, says that most successful schools share four traits and I believe these four traits are key to the kind of quality, staff-driven professional development I advocate above. In all the most successful schools: 

  • Teachers talk about learning: Meetings are dedicated to talking about lessons, about students, and about teaching and learning in general. Meetings are never used to discuss administrative matters.

  • Teachers observe each other: Teachers engage in a planned programme of peer observations and feedback. Observations are followed by constructive, focused discussions about how teachers can improve and about how teachers can share practices and celebrate each other’s skills and talents. 

  • Teachers plan together: Teachers talk to each other about their medium and long-term planning, and about their marking and students’ work. Teachers routinely scrutinise each other’s work and moderate each other’s assessments, perhaps engaging in a process of peer review of each other’s mark books and students’ work.

  • Teachers teach each other: INSET days provide opportunities for teachers to share best practices and comment on what they have tried in their classrooms, articulating what worked and what did not.

In conclusion

I think we can all help to improve the quality of teaching and learning in our schools and colleges by following the Bayesian Method because we are better together. Moreover, together we will be outstanding.


CAPTION: Search: Dr John Craven employed the Bayesian Method of averaging the views of a range of experts to locate the missing submarine, USS Scorpion, which was found about 740 kilometres south west of the Azores, pictured, in the North Atlantic



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