This article examines how students taking a post-compulsory physics course for 16-to 19-year-olds (A-level physics) benefited from a change in pedagogy which meant that they spent more time problem solving in collaborative groups. Video analysis of these collaborative problem-solving sessions revealed that the students improved a number of key competences, including their use of metacognition. As a result, the students improved in their learning of physics, although the reasons for this differed from student to student.