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Assessment and
language intervention evidence

Learn about the academic research trials and independent evaluations carried out on our assessment apps and interventions to evaluate their effectiveness in mainstream schools. Below are the key findings from these studies providing clear insights into their impact on children’s language and behaviour in schools.

A summary of this research is available on our research overview page.

Early language screening [LanguageScreen] and intervention [NELI] can be delivered successfully at scale: evidence from a cluster randomised controlled trial (2021)

Gillian West, Margaret J. Snowling, Arne Lervåg, Elizabeth Buchanan-Worster, Mihaela Duta, Alexandra Hall, Henrietta McLachlan, and Charles Hulme
The Journal of Child Psychology and Psychiatry
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This study provides strong evidence that language intervention delivered in mainstream schools can significantly improve children’s language skills.

  • A 10-minute LanguageScreen test administered by teachers and/or teaching aides could be used reliably to identify children in need of support with language development.
  • Children receiving the language intervention demonstrated significantly larger gains in their language skills compared to the control group.
  • The positive effects of intervention were consistent across genders and among English as an Additional Language (EAL) children.

This paper was one of the top ten most downloaded research papers from The Journal of Child Psychology and Psychiatry in 2021

Early language intervention [NELI] improves behavioural adjustment in school: evidence from a randomised trial (2022)

Gillian West, Arne Lervåg, Margaret J. Snowling, Elizabeth Buchanan-Worster, Mihaela Duta, Charles Hulme
Journal of School Psychology
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This study demonstrates that a school-delivered language intervention programme has positive effects on teachers’ ratings of children’s behaviour in school.

  • Based on a large randomised controlled trial the research showed greater improvements in the behaviour of children who participated in the language intervention than those who didn’t.
  • The study suggests that the NELI program requirements such as sitting still, listening, and participating in small group and individual sessions, along with rewarding children for participating in the program, contribute to these improvements.

NELI scale-up impact evaluation (2023)

Education Endowment Fund
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This impact evaluation, conducted by NFER, evaluated the impact of NELI delivered at national scale in the UK on student’s oral language skills.

  • Children who received the NELI program made on average the equivalent of 4 months’ additional progress in language skills compared to those who did not receive the intervention.
  • Additionally, children with English as an Additional Language (EAL) made the same progress as their peers.
  • Children from less-advantaged backgrounds made the equivalent of 7 months’ additional progress as a result of participating in the NELI Program.

Training Teaching Aides to support early language development (2020)

Education Endowment Fund – Second Efficacy Evaluation
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This independent report evaluated the NELI program under everyday conditions in schools.

  • Children who received the language intervention made the equivalent of 3-5 months additional progress in language and reading skills compared to those who did not receive the intervention.
  • Children’s word reading skills also improved.
  • Additionally, children with English as an Additional Language (EAL) made the same progress as their peers.
  • Surveys and interviews revealed that schools found the training and ongoing support provided for NELI to be clear, useful, and sufficiently detailed for efficient delivery of the intervention.
  • A follow up study of children from this study showed that the gains in their language and word reading were still present two years after the intervention had finished. Such durable effects of an intervention are rare.

National scale-up of NELI to support COVID-19 education recovery (2021)

Education Endowment Fund (EEF) – Scale Up Trial
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Following successful effectiveness trials, the UK Department for Education (DfE) provided funds to scale up the NELI program to over 10,000 schools over two years. Independent evaluations overseen by the EEF explored the success of this large-scale implementation.

  • Delivering training online, and at scale, worked well with most school staff feeling prepared to deliver the intervention after training.
  • Despite challenges posed by national lockdowns and ongoing disruptions from Covid-19, teachers and teaching aides involved in the program reported a positive effect on students’ confidence and language abilities, with 70% indicating they would deliver the intervention the following year.

Improving spoken language skills in young children around the time that they start school (2014)

Education Endowment Fund – Initial Efficacy Evaluation
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This independent study evaluated the NELI Program under regular conditions in schools.

  • NELI had a positive effect on the language skills of children in the trial.
  • Staff also reported that the program had a positive effect on children’s confidence, reporting that the small group format, activities covered and the focus on narrative and vocabulary work contributed to this effect.


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