Education Endowment Foundation:Teaching Assistant Interventions

Teaching Assistant Interventions

Moderate impact for moderate cost based on moderate evidence
Implementation cost
Evidence strength
Impact (months)

Teaching assistants (also known as TAs, classroom support assistants or teachers’ aides) are adults who support teachers in the classroom. Teaching assistants’ duties can vary widely, but they are generally deployed in two ways; to support the teacher in the general classroom environment, or to provide targeted interventions, which are often delivered out-of-class. The role can also include administrative support. 

1. Teaching assistants can provide a large positive impact on learner outcomes, however, how they are deployed is key.

2. The high average impact hides a large variation between the different approaches to teaching assistant deployment. Targeted deployment, where teaching assistants are trained to deliver an intervention to small groups or individuals has a higher impact, whereas deployment of teaching assistants in everyday classroom environments has not been shown to have a positive impact on learner outcomes.

3. Access to high quality teaching is the most important lever schools have to improve outcomes for their pupils. It is particularly important to ensure that when pupils are receiving support from a teaching assistant, this supplements teaching but does not reduce the amount of high-quality interactions they have with their classroom teacher both in and out-of-class.

4. Investing in professional development for teaching assistants to deliver structured interventions can be a cost-effective approach to improving learner outcomes due to the large difference in efficacy between different deployments of teaching assistants.

The average impact of the deployment of teaching assistants is about an additional four months’ progress over the course of a year. However, effects tend to vary widely between those studies where teaching assistants are deployed in everyday classroom environments, which typically do not show a positive benefit, and those where teaching assistants deliver targeted interventions to individual pupils or small groups, which on average show moderate positive benefits. The headline figure of four additional months’ progress lies between these figures.

Research that examines the impact of teaching assistants deployed in everyday classroom environments suggests that students in a class with a teaching assistant present do not, on average, outperform those in one where only a teacher is present. This average finding covers a range of effects. In some cases, teachers and teaching assistants work together effectively, leading to increases in attainment. In other cases, pupils, particularly those who are low attaining or identified as having special educational needs, can perform worse in classes with teaching assistants.

Where overall negative effects have been recorded, it is likely that support from teaching assistants has substituted rather than supplemented teaching from teachers. In the most positive examples, it is likely that support and training will have been provided for both teachers and teaching assistants so that they understand how to work together effectively, such as by making time for discussion before and after lessons.

Research which focuses on teaching assistants who provide one to one or small group targeted interventions shows a stronger positive benefit of between four and six additional months on average. Often interventions are based on a clearly specified approach which teaching assistants have been trained to deliver.

Teachers also report the benefits in terms of workload and reduced stress from working with teaching assistants.

In England, positive effects have been found in studies where teaching assistants deliver high-quality structured interventions which deliver short sessions, over a finite period, and link learning to classroom teaching, such as:

  • Abracadabra (ABRA)
  • Catch Up Literacy
  • Catch Up Numeracy
  • Nuffield Early Language Intervention (NELI)
  • Switch-on Reading
  • Talk for Literacy

There is also evidence that working with teaching assistants can lead to improvements in pupils’ attitudes, and also to positive effects in terms of teacher morale, workload and reduced stress.

  • The majority of studies were targeted interventions conducted in primary schools – where the impact is typically a little higher (+5 months) than for secondary age pupils (+4 months).

  • Most of the evidence relates to reading and other aspects of literacy. Impact is lower for mathematics in primary schools (+ 3 months).

  • The majority of effective approaches involve targeted small group or one to one interventions. Impact in small groups tends to be a little lower (+3 months), but this needs to be offset against the greater number of pupils who benefit.

  • Short sessions of around 30 minutes or so, several times a week are most effective.

  • Approaches involving digital technology can also be effective with teaching assistant support.

Schools should carefully consider how teaching assistants are used to support learners from disadvantaged backgrounds. There is evidence that when a teaching assistant is used to support specific pupils routinely in the classroom, the teacher may interact less with these pupils, meaning that those who need additional teacher monitoring and support may not receive it. Therefore, additional care should be given to how teachers respond to the deployment of teaching assistants and who they are supporting, particularly for previously low attaining or disadvantaged pupils.

However, well-evidenced teaching assistant interventions can be targeted at pupils that require additional support and can help previously low attaining pupils overcome barriers to learning and catch-up’ with previously higher attaining pupils.

Schools should carefully monitor teaching assistant interventions to ensure they are well-delivered, so that pupils receive the large benefits of structured interventions and not the limited impact of general deployment.

Teaching assistant interventions have an impact through providing additional support for pupils that is targeted to their needs. In order to have the desired effect schools might consider:

  • Careful assessment of pupils’ needs so that teaching assistants support is well targeted
  • Training teaching assistants so that interactions are high quality – for example, using well-evidenced targeted programmes
  • Ensuring that any interventions are well-linked to classroom content and do not reduce high quality interactions with teachers

High quality communication between teaching assistants and classroom teachers is likely to support good implementation of teaching assistant interventions. Studies were not included where the TA was assigned as SEND support for an individual pupil as part of an SEND plan. 

Teaching assistant interventions are typically delivered over half-term or term-long periods when adopting a targeted intervention or approach, or across the entire academic year when used as more general deployment.

When introducing new approaches, schools should consider implementation. For more information see Putting Evidence to Work – A School’s Guide to Implementation.

Overall, the median costs of implementing teaching assistant interventions are estimated as moderate. The costs associated with the effective deployment of teaching assistants arise from staff salary expenses, the majority of which are recurring costs.

Whilst the median cost estimate for the effective deployment of teaching assistant interventions is moderate, differences in training and resource costs through specific teaching assistant taught programmes or interventions means that costs can range from very low to high. Evidence suggests that the more effective approaches are structured and involve high-quality support and training, so it is important that teaching assistants have professional development in the pedagogy and content of the specific intervention they are expected to use.

These cost estimates assume that schools are already paying for teacher time to work with and support teaching assistants, and the facilities and materials required to implement a teaching assistant intervention. These are all pre-requisite costs of using teaching assistant interventions, without which the cost is likely to be higher.

The security of the evidence around teaching assistant interventions is rated as moderate. 65 studies were identified.

Overall, the topic lost an additional padlock because a large percentage of the studies were not independently evaluated. Evaluations conducted by organisations connected with the approach – for example, commercial providers, typically have larger impacts, which may influence the overall impact.

Evidence strength
Number of studies65
Review last updatedJune 2021