What`s the evidence on…..the impact of teaching assistants?

If you are a parent or teacher of a child with special educational needs, who struggles to stay focused in class, you might think extra support from an additional adult would help. Well, yes and no.

Results from studies of the impact of these adults, known variously as teaching assistants, learning support assistants or classroom assistants, appear contradictory.

The Education Media Centre is building a series of articles setting out the research evidence on a range of education issues which interest journalists and matter to the public.

Here, Rob Webster, a leading researcher on the impact of teacher assistants, helps makes sense of the evidence.

Any opinions expressed are his own.

In England teaching assistants make up a quarter of the school workforce. The number has tripled since 2000 and according to the DfE, there are currently around 318,700 individual TAs in English mainstream schools.

The increase in TA numbers has been based on an assumption, rather than solid evidence, that this support would help raise academic standards, and if you ask teachers whether having a TA in the classroom improves pupils’ learning you get an emphatically positive response.

Headteachers and teachers often report that using skilled TAs to take on routine admin tasks and cover lessons reduces stress, eases workload, and allows more time for planning, marking and assessing. This, some teachers claim, improves their teaching and, in turn, pupil attainment.

It`s also claimed that TAs help the development of pupils ‘soft skills’ (e.g. independence and confidence) that underpin learning, and that having a TA allows the teacher to give more attention to the rest of the class, who will make better progress.

There is little consistent evidence to support either of these claims.

Most of the research does not investigate whether TAs make a difference to pupils` success in this indirect way; instead it has mainly focused on whether TAs help raise attainment when they themselves teach and instruct children using particular methods, often in literacy and numeracy, but in other areas too.

So what does the evidence say on that? Does direct input and support from TAs affect academic outcomes and, if so, is that effect positive or negative?


i. Primary and secondary-aged pupils do tend to make progress in literacy and numeracy catch-up programmes delivered by TAs, often away from the classroom, when TAs are properly trained and supported to do so.

ii. But pupils in mainstream schools supported for most of the time by a TA make much less academic progress than similar pupils who receive little or no TA support. Read more here.

iii. The negative effect is most marked for pupils with high-level special learning needs, for example those with Statements Read more here.

iv. Also, pupils with Statements in mainstream primary schools experience a high degree of separation from their class, teacher and peers, which is likely to explain why both their education and their social development suffers. Read more here.


Looking at the evidence on the impact of TA support given to primary and secondary-aged children outside the class, using specific techniques and programmes to help them catch up in numeracy and literacy, most of these studies found pupils did make progress but only when delivered by TAs who had been trained in those programmes.

Some recent results of research into literacy and numeracy interventions support this. The researchers conducted randomised control trials, where results from a group of pupils who received support from TAs trained in these programme were compared with results from control groups who did not receive the programme or received an alternative form of support from TAs.

A word of caution about studies like this: firstly, not all of them separate the effects of TA support from the intervention itself. So we can`t always be sure how much progress is down to the programme and how much to TA support. Secondly, many of these studies fail to ask whether the impact would have been greater if the programme had been delivered by a teacher rather than a TA.

However, there are studies which do show experienced and specifically trained teachers get better results than TAs.

I was a researcher on the largest study of the impact of teaching assistants carried out in the world. The Deployment and Impact of Support Staff (DISS) project looked at 8,200 pupils in seven year groups, across 153 primary and secondary schools.

We found that TA support in core subjects and over a school year had a consistent and significantly negative impact on pupils` academic progress.

The pupils receiving most TA support made less progress than similar pupils who received little or no TA support, even after taking into account factors like prior attainment and whether the child had special needs.

The DISS project results are surprising and counterintuitive, but help reveal the difference between the effects of TA support in the classroom and in TA-led interventions outside of it. Pupils are often withdrawn by the TA from the class for catch-up programmes, and as a result, become detached from the teacher. Gains made via interventions are at the expense of missing parts of the curriculum and a pupil`s overall annual attainment, for which we must account.

As yet, there are no research studies that have examined this. However, based on what we do know, we might, for now, reasonably conclude that progress made in TA-led interventions away from the class does not translate into overall and end-of-year attainment

So although it seems largely proven that appropriately trained TAs can have a positive impact on struggling pupils with one-to-one tuition in certain programmes, outside of the classroom; despite what teachers might think, the evidence suggests it does not follow on that TA support in the classroom helps a pupil`s overall progress.

Some will find these messages from the research disquieting. So how do we reconcile them, and what might they mean for school improvement?


As a researcher on the DISS project and subsequent studies exploring more effective use of TAs and the educational experiences of pupils with high-level SEN, it is clear to me there are two key reasons why TAs might have little impact on academic progress. Both are about decisions schools make about TAs, rather than decisions made by TAs. Put simply, TAs are not to blame, and it`s essential to grasp that to avoid arriving at unhelpful conclusions about what to do next.

The first reason concerns the gap between the learning outside and inside the classroom. When interventions are an “add on” to the curriculum for lower attaining and SEN children, and it is left to those pupils themselves to make the links between learning outside the classroom and what`s being taught back in class, the TAs’ valuable contribution gets undermined.

Therefore, schools must make interventions, delivered by properly trained TAs, part of a coherent, integrated package of learning for those falling behind.

The second reason is dealing with the issues of TA deployment throughout the school day.

On the basis of the available evidence, it can be argued schools must fundamentally rethink how they use TAs and ensure they add value to teachers, not replace them.

We need to make sure TAs are not given primary responsibility for pupils in most need and are used in ways to allow teachers to spend more time with these pupils.

Allied to this is the need to develop what we might call an improved teaching method for TAs: a way of interacting with pupils using effective styles of questioning to promote and support independent learning.

Finally, we need to guarantee time for teachers and TAs to liaise and seriously invest in TAs’ professional development.

We do not underestimate the challenges facing schools, operating under the scrutiny of Ofsted and within budget constraints. Yet we have found in our work with schools that real change and significant progress can be made, which does not break the bank. And until policy makers and school leaders seriously engage with this process, the enormous potential of TAs, in terms of their contribution to and impact on pupils` achievement, will not be fully realised.


Rob Webster is a researcher at the Institute of Education, London, where he also leads the Maximising the Impact of TAs (MITA) programme. 

For more on the research and the MITA programme and conferences, please visit www.maximisingtas.co.uk




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