My first term as a teacher was the hardest. It was obvious that my pupils assumed I’d soon join the ever-growing trail of teachers who had come and gone from their school in the years running up to my arrival in September 2006, and they treated me with the level of respect they thought this deserved.

Teacher turnover was already a problem back then, but 16 years later the number of teachers leaving the profession has crept inexorably higher. And, unfortunately, that trend looks set to continue. 

The latest school workforce data shows that the five-year retention rate is dropping. And, according to a recent report from SchoolDash, the Gatsby Foundation and Teacher Tapp, advertised vacancies in schools have increased by 14 per cent compared with three years ago.

Researchers like me have written reams of reports about how to stem the leaks in the teacher supply pipeline. But what is rarely discussed is how teacher turnover affects pupils and what to do about this.

The impact of teacher retention problems

So, what effect, if any, does teacher turnover have on learning? And what steps can schools take to minimise any negative impact?

There are three main issues to consider here.

1. Trust

According to Miles Huppatz, a head of department at a secondary school near Peterborough, the main casualty of staff turnover is the strength of the relationships between pupils and teachers. This, he explains, has a knock-on effect on learning.

“When you have good relationships, it’s so much easier to have a good classroom environment,” Huppatz explains. “There’s this element of familiarity that is particularly pronounced for pupils with SEND [special educational needs and disabilities] and those with challenging behaviour. It takes time to build up trust, but high turnover can make the school feel unfamiliar for them all over again.”

He gives the example of one pupil whom he has been teaching for two and a half years.

“We’ve come a long way in that time,” he says. “He was one of the most challenging pupils, but I’ve now been able to build a working relationship with him.”

Back in my first year of teaching, I experienced something similar. By the time I returned to the classroom after the Christmas holidays, my relationships with pupils were already changing for the better.

It’s a process that economists who study “game theory” can help to explain.

Game theory is the study of situations in which two or more people or parties make strategic decisions in relation to one another. In the classic game theory model of the prisoners’ dilemma, two people have a choice when caught doing something wrong: they can either betray their accomplice or stay silent.

If both stay silent, they share the penalty and go to prison for five years each. If they betray each other, both get locked up for 10 years. If only one betrays the other, the betrayer gets off scot-free and only the silent accomplice goes to prison for 10 years.

The worst possible outcome is for both parties to blame each other, yet this is almost always what ends up happening. This is because cooperation requires a huge amount of trust. 

A similar dynamic exists between teachers and pupils; both benefit from avoiding misbehaviour and sanctions, but they often get tied up in mutually destructive cycles of tit-for-tat disruption and punishment.

‘High teacher turnover can make the school feel unfamiliar for pupils all over again’

Fortunately, the prisoners’ dilemma shows that this cycle can be broken and that the betray-betray outcome is not inevitable.

Economists have found that if the prisoners’ dilemma is repeated enough times, trust eventually emerges and cooperation ensues. It is, therefore, no wonder that teacher-pupil relationships shift over time and that consistency gradually yields mutually beneficial cooperation.

Rebecca Cramer is executive headteacher at Reach Academy Feltham, an all-through school in West London that has stretched its remit into the early years and family support. She is a big advocate of the benefits that can accrue from long-term relationships. 

“We meet some of our students when they are in the womb. We are with them as they deal with the ups and downs of life and go through the rites of passage of growing up. Building up the trust that comes with that can be the difference between success and failure,” she says.

Huppatz agrees with her. “Over time, you learn to spot what mood a challenging pupil is in when they step through the classroom door and you can adapt to that, or you see them around the school and know to ask them how their football went at the weekend,” he explains.

Of course, the problem is that when teachers move on, it can derail pupils’ sense of safety and predictability. Schools operating in high-turnover environments, therefore, need to actively engineer trust.

One approach is to develop cooperation through predictability at a school level, rather than just relying on individuals. This is where routines can make a difference, according to Cramer.

She finds that “explicitly teaching and constantly refreshing routines means pupils don’t have to guess what is expected of them. This helps pupils to relax and focus on their learning because they’re never in the fight-or-flight mode that typifies unpredictable, low-trust environments”.

Another approach is to speed up the emergence of cooperation and trust by actively nurturing relationships. The Relationships Foundation, an organisation based in Cambridge, has been exploring how to do this for the past eight years. It has found that planning residential ”expeditionary learning” activities can kick-start relationship building.

According to the foundation’s director, John Ashcroft, “being in a different context can forge connectedness, belonging, understanding, respect and an alignment of purpose and goals”.

Most schools still organise residentials at the end of the school year, but evidence from The Relationships Foundation’s work suggests that earlier in the year might be a much more beneficial time to run such trips.

2. Institutional knowledge

Trust isn’t the only factor at play when it comes to the importance of continuity in schools, though, as further evidence from across the Atlantic shows.

Matthew Ronfeldt is an associate professor at the University of Michigan. He and his colleagues are responsible for a series of studies tracking the impact of teacher turnover on pupils. In one study from 2013, they crunched 625,000 pupil data points to see who was affected by turnover and how. Their findings paint a stark picture of the damage caused by “churn”, showing that minority-ethnic and low-attaining pupils are the worst affected.

It’s easy to assume that the harm that turnover causes is primarily down to falling teacher quality, as effective teachers are replaced by less experienced colleagues. However, Ronfeldt and his co-researcher were alert to this possibility and controlled for the replacement teacher’s effectiveness. Their conclusion was clear: churn itself seemed to be doing the damage.

‘Schools need to get induction and mentoring right for every new teacher’

So, what was going on? According to the researchers, teachers leaving results in a loss of institutional knowledge about how the school works.

That certainly rings true from my experience. While life as a teacher got easier for me after that first Christmas, the real transformation came when I stepped into the playground at the start of my second year in school. Suddenly I felt more relaxed. I knew exactly how things worked. I was confident about what was and wasn’t normal or acceptable, so pupils no longer had the upper hand. I’d become a sort of expert in “how things work around here”.

Schools, therefore, need to get induction and mentoring right for every new teacher, not just newly qualified teachers. 

As the headteacher I worked with put it, “only once the most ropey supply teacher can walk in and teach without disruption will we have succeeded”.

3. Collaboration and collegiality

In Ronfeldt’s study, loss of institutional knowledge was shown to be a key problem associated with teacher churn.

But the researchers found that the impact of turnover went even further. Teacher churn didn’t just harm pupils in the classes whose teachers left; the effect seemed to spill out across the school.

One explanation is that this effect Ronfeldt and his colleagues were measuring was actually down to a hidden variable, such as poor leadership. However, he argues that the culprit was a reduction in staff collaboration and collegiality.

In a subsequent 2015 study, he and his colleagues zoomed in on that hypothesis and, sure enough, they found a link between levels of staff collaboration and pupil achievement - though a recent English study did not reveal a link between attrition and collaboration.

The traditional Friday night at the pub can play a big part in nurturing collegiality, according to Becky Allen and Sam Sims. In The Teacher Gap, their book about how to tackle England’s recruitment and retention crisis, they argue that it forms “an integral part of the working week”, providing a “collective shoulder to cry on” as well as an opportunity to exchange information.

They go on to tell the story of Abi, an early career teacher (ECT) stuck in a school with limited informal networks, who ended up feeling isolated as a result.

Friday nights at The Elgin Arms, down the road from my school, certainly played a crucial role in my own developmental journey, helping me to build my “social capital” - my network of trusting relationships. They also provided an opportunity to exchange knowledge and advice about different classes.

A high-turnover environment necessitates new ways of nurturing esprit de corps and of providing space for informal CPD. These opportunities should be inclusive of teachers from all cultures and accessible to those with caring responsibilities.

How new is ‘new’?

We know, then, that teacher churn can lead to a breakdown of trust, a loss of institutional knowledge and a reduced sense of collegiality. 

It’s important that schools take steps to mitigate these problems, but there are also several additional questions that leaders should be asking.

So far, we’ve considered the impact of teachers leaving a school completely and being replaced by another teacher. But there is actually a lot more nuance to this issue. 

As another American study shows, “newness” isn’t a binary. In other words, some teachers have taught the same class in the same school for several years, whereas others are veterans of a school but have been allocated a new class. Meanwhile, a third group might be new to the school but have already worked in the same community. At the other extreme are teachers moving from a different geographical area, as well as trainees and ECTs.

To map how this spectrum of newness relates to pupil achievement, Allison Atteberry and her colleagues dug into more than 10 years of data from nearly 180,000 teachers in New York for a 2017 study. Their conclusion was that the newer a teacher was, the less highly pupils achieved. They concluded that “it is more difficult to be effective at complex tasks when the task or context is unfamiliar”.

‘As teachers and pupils grow more familiar, they adjust to each other’

As Allen and Sims point out in their book, teachers constantly make professional judgements based on a mental database of past examples. The more relevant the cases stored in this database are, the more useful the analogies they can draw.

Recruiting staff with a more relevant mental database, or helping them to stock their database as quickly as possible, might therefore help to maintain teacher effectiveness in high-turnover environments.

Are we missing a trick on teacher allocation?

There is an important overlap between Ronfeldt and Atteberry’s conclusions that raises some tough questions for school leaders. Both researchers found that although disadvantaged pupils benefit the most from continuity, it’s these pupils who experience the most churn.

The reason for this isn’t just that disadvantaged pupils are more likely to attend schools where teacher turnover is high; even within the same school, disadvantaged pupils are more often allocated to newer teachers. But why?

Although it’s important to remember that the evidence on this trend comes from the US, there are signs the same pattern is replicated in England.

New data from Teacher Tapp shows that more than half of teachers have at least some influence over their timetable, or over which pupils they teach. On top of that, more senior teachers have even greater influence.

Unfortunately, the class everyone is fighting for is rarely the most challenging class. In fact, research by the Sutton Trust shows that 69 per cent of teachers prefer to teach classes with higher-attaining pupils.

Like the proverbial small kid who never got picked for the football team (that was me), there’s a risk that classes with a high concentration of lower-attaining or disadvantaged pupils are left until last, and that the very pupils who most need continuity are the ones most likely to experience churn. Schools should therefore be careful of the unintended consequences of allowing individuals to influence the timetable.

Could ‘looping’ help?

Teacher allocation is too important to be left to chance and “looping” is one approach to optimising it. 

“Looping” is a term used to describe pupils being allocated to the same teacher more than one year in a row, whether at primary or secondary school.

In 2004, researchers Peter Cistone and Aleksandr Schneyderman found that teachers and pupils alike reported better relationships under looping. Since then, a number of studies have found that the practice has a positive impact on attendance, behaviour and exam attainment, including research from Matthew Kraft published earlier this year.

These findings aren’t surprising, given Atteberry’s conclusions, but they do raise questions as to why looping isn’t more common. Perhaps this is just because these US findings aren’t particularly well known in England - even the Education Endowment Foundation has yet to look into the approach.

Another possibility is that parents and pupils can be concerned about being stuck with a teacher they don’t get on with, while teachers may be keen to move on from a class they find difficult. 

However, even the least effective teachers have been shown to improve when they’re working with a familiar class. In fact, in 2018, Andrew Hill and Daniel Jones found that the strategy could have even greater impact on the effectiveness of less-skilled teachers.

A study entitled Second Time’s the Charm?, led by Leigh Wedenoja, suggests this is because as teachers and pupils grow more familiar, they adjust to each other - just like Huppatz did when he became more attuned to his pupils’ mood, and just as the prisoners do in the economists’ model. If some teacher-pupil matches will always work out better than others, it makes sense to maximise everyone’s effectiveness by promoting continuity.

In any case, if there are concerns about a teacher’s effectiveness, then support and performance management are surely more sensible responses than an endless game of musical chairs. Even the quest for continuity shouldn’t come at the expense of high standards. 

Given the potential significance of teacher allocation, more research is urgently needed on this side of the Atlantic. A proper study could also help timetablers to navigate a tricky tension in the research: although on the one hand, moving teachers up with pupils improves achievement, other studies show that workload can be reduced and teacher effectiveness improved when teachers teach the same year-group or content multiple times.

Can we do more outside of lessons?

Ultimately, Ashcroft’s view is that “we should see relationships as stories”. This means accepting that continuity does not mean “ossification, or that nothing changes”; instead, it’s about maintaining “narrative continuity” in schools. 

For him, “the narrative thread is like a many-stranded rope: so long as a pupil has multiple strong relationships, even if one is broken the cord won’t be ruptured”.

The Relationships Foundation, therefore, recommends prioritising the role of pastoral leads, form tutors and heads of year. It also argues that improved management information systems can smooth information handover, while extracurricular activities can create opportunities to maintain relationships outside of lessons and independent of class allocations.

Meanwhile, although interventions provided by external organisations can sometimes add to churn, that needn’t be the case if schools opt for long-term partnerships. Link workers from West London Zone, for example, work closely with identified pupils and their families, staying with them over several years and helping to join up multiple relationships around each child.

As teacher turnover creeps ever higher, pupils are being deprived of the continuity they crave. This erodes trust and cooperation, causing problems for pupils who lack continuity elsewhere in their lives.

Tackling teacher churn clearly depends on improving retention, but in the meantime, there are steps that schools can take to mitigate the corrosive impact of turnover.

The solution is likely to involve nurturing trust and relationships, providing stability and predictability at an institutional level, and carefully allocating teachers to minimise disadvantaged pupils’ exposure to disruption.

Loic Menzies is a former chief executive of The Centre for Education and Youth and a visiting fellow at Sheffield Institute of Education. He is currently writing a book on education policymaking for Routledge. He tweets @LoicMnzs