Ability grouping in classrooms does not stall weaker students’ progress, research finds

High-achieving secondary school pupils make significantly stronger progress in mathematics when taught in classes grouped by ability, according to a landmark study that challenges long-held assumptions about mixed-attainment education. The research, led by University College London’s Institute of Education and backed by the Education Endowment Foundation (EEF), found that high-flyers in mixed-ability classrooms fell behind by an average of two months compared with their peers in schools that used setting by attainment.

Clear gains for top performers

The study, which examined maths attainment and self-confidence among Year 7 and 8 pupils (aged 11–13) in 97 state schools across England, compared 28 schools with mixed-ability classes against 69 similar schools that organised pupils into sets by prior attainment. Among students who had previously achieved highly in maths, those in mixed-attainment settings made slower progress than those taught alongside children of comparable ability. Over the course of the study period, the gap amounted to two months’ less progress for high-attaining pupils in mixed classes. The overall effect across all pupils was one month less progress in schools that did not use setting.

The researchers noted that, despite “well-intentioned policies in mixed-attainment schools around equity and challenge for high-attainers, only setting schools appear to be challenging high-prior-attaining students.” They also pointed out that while mixed-ability schools showed a narrower gap between their best and worst performers, this was “driven by lower progress among the high-prior-attaining students, rather than greater progress by the low-prior-attaining group.”

Becky Francis, the EEF’s chief executive, said the direct comparison between the two approaches was what made the study “innovative and revealing.” She added: “What we found is that there was very little difference for low-attaining young people between mixed-attainment and setting classes. Meanwhile, for the high-attainers who make strong progress in high sets, they make lower progress in mixed-attainment classes overall.”

Professor John Jerrim, a UCL education and social statistics expert who was not involved in the research, described the outcome as “big and important.” He argued that the EEF should now “come out and support achievement grouping in maths”, pointing to the finding that it “has no negative impact on lower-achievers, some positive benefits for high-achievers, and helps teachers manage workload.” Jerrim also took aim at past academic criticisms of ability grouping, saying: “It wasn’t long ago that some educational researchers in the UK and Ireland were calling ability grouping ‘symbolic violence’. I think this work – and other evidence – shows the need for more restraint from academics.”

Low-achievers not harmed

One of the most striking findings of the study is that setting by attainment did not “significantly harm the attainment of low-prior-attaining or socioeconomically disadvantaged” pupils. This challenges a body of previous research that had warned of negative effects on self-confidence and learning opportunities for lower-attaining students, with some critics fearing a “cycle of restricted opportunity” and the risk that socioeconomic background could influence allocation into lower sets. The new evidence offers a counterweight to those concerns, at least in the context of mathematics teaching in English secondary schools.

The study also examined pupils’ self-confidence in maths, finding that those in mixed-attainment schools reported lower levels of confidence compared with their counterparts in schools using setting. This result runs counter to earlier reports that had suggested setting damages the confidence of pupils placed in bottom sets.

The EEF’s own Teaching and Learning Toolkit, a widely used resource, has previously indicated a negative effect size for ability grouping on overall student achievement, though that finding has been debated and contrasted with other meta-analyses. A separate project, the “Best Practice in Mixed Attainment Grouping” evaluated by the National Foundation for Educational Research for the EEF, encountered difficulties because schools were reluctant to participate in evaluations and one trial struggled to draw firm conclusions due to implementation issues.

Teacher allocation remains critical

Despite the overall positive picture for setting, the study issued a clear warning: for ability grouping to work effectively, schools must avoid allocating their best teachers exclusively to the top sets. The researchers cautioned that such a practice could undermine the benefits of setting for lower-attaining pupils, who would then miss out on high-quality instruction.

Pepe Di’Iasio, general secretary of the Association of School and College Leaders (ASCL), said school leaders were “best placed to make decisions about setting, as they best know their context and the needs of their pupils.” He added that the research would be “extremely helpful” in informing those decisions, but stressed that “the essential ingredient is, of course, having sufficient numbers of specialist maths teachers to ensure that pupils at all attainment levels receive the best support possible.”

Di’Iasio highlighted the persistent shortage of maths teachers in England, noting that recruitment targets for the subject have been missed every year since 2012/13. “Unfortunately, there is a longstanding problem with recruiting maths teachers and many schools have no choice other than to use nonspecialists and supply cover,” he said. The broader context of educational disadvantage also looms over the debate: attainment gaps between disadvantaged pupils and their peers have widened since 2019, with pupil absence identified as a key driver. Becky Francis has previously emphasised that effectively supporting students with special educational needs is a crucial part of closing the disadvantage gap.

The study, part of the “Student Grouping Study” run by UCL IOE and funded by the EEF, ran from 2019 to 2025. It comes against a backdrop of fluctuating policy: setting became common practice in English secondary schools from the 1990s, with a Labour government policy in 1997 stating that “setting should be the norm,” while mixed-ability teaching had gained traction in comprehensive schools during the 1970s before facing renewed scrutiny. The efficacy of any grouping strategy, the research makes clear, is heavily dependent on the quality of teaching and the way sets are managed—including fluid movement between groups and careful naming conventions that can mitigate some perceived disadvantages.