Simple ways of checking that pupils understand a topic during a lesson, such as showing their answers on chalk slates, can boost their progress by two months, a study has found.

Year 11 pupils who demonstrated their answers in “real-time” in classrooms, during a trial by the Education Endowment Foundation, pulled ahead in their learning.

Teachers in 140 secondary schools asked their pupils to show their responses to a question at the same time, for instance, by holding up answers on a slate or mini-whiteboard.

The teacher then decided whether to review the material with everyone, identify a small number for help or ask pupils to discuss with peers.

Of 25,000 pupils who took part, those with teachers trained to deliver this formative assessment method during lessons made two months’ additional progress.

The impact on their Attainment 8 scores was 0.10 when measured as an effect size, and as such is statistically significant. However, further evidence is needed on the impact of the practice on free school meals pupils, for whom the difference was 0.07.

Informal assessments are encouraged across many schools but can often be difficult and expensive to implement, the EEF report noted.

The three-year programme cost about £3,895 per school.

Stephen Gorard, professor of education at Durham university, said the cost might be even lower per pupil if teachers continued to use the same method in the future.

But he pointed out that the effect size was still low and so he “wouldn’t shift a huge budget into this at the moment”.

The volunteer teachers involved were also necessarily enthusiastic about improving their formative assessments, he added. Across all schools, the effect size might not be so significant.

Johnny Runge, co-author of the report, said the monthly workshops on the methods were “valued” by teachers and probably an “important factor” in the programme’s success.