Primary and secondary schools in England employ 342,000 teaching assistants (TAs). That’s comfortably more than the entire population of Iceland.

TAs also represent the single biggest investment of pupil-premium funding and are frequently cited as essential to facilitating the inclusion of some of our most vulnerable learners.

Indeed, so fundamental are TAs to our system, that when TAs in Derby went on strike last year, schools were unable to open.

But unfortunately, few TAs are used as effectively as they should be. Most TAs spend the majority of their time supporting lower-attaining pupils and those with SEND in lessons across the curriculum. Yet, perhaps counter-intuitively, the research evidence shows that this is one of the least effective ways to improve outcomes for struggling pupils.

The not unreasonable, commonsense view is that the children who struggle the most need more individual and small-group support, and this tends to come via TAs. Yet this arrangement has unintended consequences. Pupils who require high-quality teaching the most, receive it the least. Separation from the classroom, teachers and the curriculum is a key factor in why pupils who get the most TA support perform less well academically than those who receive little or no support - regardless of whether they have an underlying special educational need and disability.

The central issue is not that TAs are ineffective, but that school leaders and teachers don’t always make the best decisions about how to deploy them, or how to position TAs in relation to wider efforts to improve outcomes for disadvantaged learners.

So, what could schools do differently?

1.   Don’t see TAs as a resource only for children with SEND

First and foremost, TAs shouldn’t be used as an informal teaching resource for disadvantaged learners and those with SEND. The first line of defence in raising attainment is ensuring that teachers spend at least as much time with these pupils as they do with others.

2.   TAs and teachers should share teaching

Teachers should be aware of the ways they can use TAs during lessons to free up opportunities for them to work with struggling pupils. For example, set up the classroom in such a way that on day one, the teacher works with one group, the TA with another, and the other groups complete tasks collaboratively or independently. Then, on day two, the adults and activities rotate, and so on throughout the week.

3.   TAs should be visible

Confident TAs could have a more visible role in teaching, scribing answers on the whiteboard or demonstrating equipment, allowing the teacher to maintain eye contact with the class.

4.   Roles should be clearly - and repeatedly - defined

A Sendco I know talks about teachers and TAs “knowing their dance routine”. Specifying their co ordinated, but differentiated, roles at various stages of a lesson can help classroom teams develop and embed practices that work in their contexts. When the arrangement works at its best, teachers and TAs work together to ensure that the teacher’s expertise is directed where it’s most needed, with the TA providing an essential service in triaging and maintaining on-task behaviour.

On the basis of sheer number and capacity, there is some serious potential we can unlock within our TA workforce. But it’s essential that school leaders take a wider view of how TAs can support learning and improve outcomes in direct and indirect ways.

Unlike in many other areas of school management and leadership, headteachers have real freedom to redefine and repurpose their TA workforce in ways that work for their settings.

The essential question leadership teams need to answer is this: what do you want the role and contribution of TAs to be in your school?

Rob Webster is director of the Maximising the Impact of Teaching Assistants (MITA) project and a researcher at UCL Institute of Education

For free downloadable guidance and resources on making better use of TAs, visit maximisingtas.co.uk