Neil Mercer has done a lot of research on group discussion in classrooms and has found that simply asking students to work together in groups is often a waste of time. Students need to have opportunities to learn how to talk together productively in groups. Here is Professor Mercer making a plea to schools to teach pupils how to have reasoned discussions together:
A quick way to get started is to simply ask your students what a good discussion looks like, and also what a bad discussion looks like! Giving them the opportunity to think and talk about this is a gamechanger.
More on group talk
A book exploring another helpful structure to promote high-quality talk
The importance of taking a moment to look and listen carefully