The research, by academics from the Eindhoven University of Technology, University of Nicosia and University of Cambridge, used survey data from over 200 teachers who participated in the original project. These revealed that structured conversations among the teachers, which are a distinctive feature of Research Lesson Study, were the principal mechanism through which they acquired both a practical grasp of different teaching techniques, and a deeper understanding of why those approaches might help struggling students.

Research has long pointed to the benefits of collaborative, classroom-based teacher learning; but what exactly should happen in those collaborative settings has been unclear. Dr Pete Dudley, from the Faculty of Education, University of Cambridge, described the findings as a “Holy Grail” in teacher development.

“Dialogue and talk provided the engine through which some essential aspects of teacher learning we constantly strive for in professional development came together,” he said. “That understanding of how and why certain approaches work, which Research Lesson Study enabled, is something that you usually only see very rarely in teacher professional development, but it is incredibly powerful.”

The Research Lesson Study project ran for two years, involving 96 primary, secondary and SEND schools. Many of the students involved were from lower income and migrant families. Almost all spoke English as an additional language, which added an extra layer of challenge to teaching complex maths.

Research Lesson Study adapts a Japanese approach to teacher development, incorporating work on oracy by Professor Neil Mercer at the University of Cambridge. In it, small groups of teachers plan and observe lessons, focusing on a particular area of learning. Between lessons, they evaluate and analyse the results together. These conversations are steered by ground rules to encourage effective dialogue: for example, teachers commit to respecting any ideas raised, and to critically evaluating every suggestion.

The project coincided with the Government’s introduction of a new maths curriculum in 2015. Findings published in 2019  showed that the mathematics rankings of 22 participating Camden primary schools subsequently rose against the national average by 2%, while those of neighbouring primary schools, which had not taken part, experienced an equivalent decline; therefore representing a 4% gap. The new study surveyed 200 of the teachers involved to understand why this happened.

The researchers were particularly interested in how far Research Lesson Study had produced cases of ‘meaning-oriented’ learning. Jan Vermunt, who was part of the research team at Cambridge (now University of Eindhoven), has shown that teachers typically learn in one of two ways. The first of these, ‘application-oriented learning’, occurs when teachers grasp how to apply teaching principles in the classroom, and has some effect on student outcomes. The second involves focusing on abstract and general principles, and has little to no effect on student attainment.

Meaning-oriented learning is a third form, which occurs when teachers also work out if, how and why certain approaches are successful with students. Although it is rarely seen in school-based teacher development, in the case of the Research Lesson Study project, it was abundant.

The new study found that high-quality dialogue was decisive. Cases in which teachers felt they had undergone effective conversations during the project were closely associated with responses to the surveys which indicated high levels of meaning-oriented, as well as application-oriented, learning. In short, exploratory talk enabled them to understand both what to do, and why it worked.

Dr Paul Warwick, an Associate Professor of Education at the University of Cambridge, said: “Exploratory talk created a space where teachers could both imagine what learning should look like, and relate that to their observations of the research lessons and to their wider experience. Working through those ideas and observations together enabled them to adopt, and adapt, more successful approaches to teaching difficult subject matter and share them with colleagues. That is probably why we saw such a positive impact on students’ learning.”

The report recommends the broader adoption of Research Lesson Study and classroom-based enquiries by groups of teachers, particularly in cases where schools are trying to strengthen learning in parts of the curriculum where attainment is weaker, or teachers themselves lack confidence or expertise.

Dudley added that the approach could help integrate effective oracy practices in schools more broadly. “If teachers are learning through talk themselves, they are likely to develop their grasp of how talk-rich approaches can be used profitably with students,” he said. “That should help to further embed an approach it is widely felt should be a more common feature of classrooms as a whole.”

The study is published in Teaching and Teacher Education.