Most teachers are "useless" at ensuring that proper group discussion takes place in their classes, a leading teacher trainer has warned.
Neil Mercer, a Cambridge University education professor, says group work is a vital part of teaching because neuroscience shows the brain is designed to learn in collaboration.
"We don't just exchange information when we talk; we actually create new knowledge together," he said. "From learning to reason together they (pupils) get better at solving problems on their own."
Teachers need to allocate enough time to allow pupils to work out answers between themselves, according to Professor Mercer. But too many were asking children closed questions that focused on whatever nugget of information was in the teacher's own head.
He said research showed that group work was "dynamite" for helping pupils to learn.
But there was a paradox, he said, at a Cambridge International Exams conference: "The research equally strongly shows that in most classrooms, most of the time, it is a complete waste of time.
"Most group work is useless and might as well not be going on," he said.
Mary Bousted, general secretary of the Association of Teachers and Lecturers, said: "This is an issue. Teachers want to learn these things and want to do them better.
"But they have not been given the opportunity to do so in the quick-fix, one-size-fits-all approach encouraged by the National Strategies.
"Teachers need really good continuing professional development in encouraging whole-class discussion and in promoting and supporting group work."
Professor Mercer said group discussion work is a weakness for teachers throughout the world.
He said pupils first needed to be told how to conduct a reasoned discussion - just as they might be taught science or maths - but teachers too often assumed they already knew.
Professor Mercer told The TES he believed that at least one- third of pupils in England lacked group discussion skills.
To make the most of effective group work, teachers need to know how to recognise it and how to teach pupils the skills they need to participate in it, he said.
"Some people think I am attacking the habits of working-class children, and I am saying we have all got to learn to talk like posh people," he said.
"But I am not saying the way they talk in the rest of their lives is a problem.
"I am saying they should be able to expand their repertoire to have a reasoned discussion.
"If they are not going to learn that at school, then where are they?"
Professor Mercer said research showed that where discussion groups agreed to work towards a common solution, pupil learning outcomes showed significant improvement.
He said primary teachers could have their classes conducting effective group discussions within three weeks.
For secondary teachers who saw a class for only a few hours a week, it might take a term.
Cambridge University's education department is in a minority in explicitly covering these skills with teacher trainees, he said.
Group goals: A fair hearing
Professor Mercer says teachers need to set pupils ground rules for class discussion.
- Everybody's point of view should be heard.
- You can only question other people's opinion if you have another idea to offer.
- The group should agree to work to find a common solution.
- Original headline: Teachers branded `useless' at class discussion by training expert