By walking around the room and looking at learners' answers, the teacher can establish quickly what has been grasped and what needs to be reinforced. A second advantage is the mental involvement of each pupil, whereas some pupils switch off during an oral plenary. A third is that lessons can end far more calmly when pupils are writing rather than clamouring to call out answers. Finally, while we could take the pupils' responses home and mark them, it is quicker - and more beneficial - to go through the answers together while the questions are still fresh in their minds.
To support learners, I try to ensure that the answers to my plenary questions are easily located on the board or in the pupils' books. This way, pupils who didn't grasp a point are supported in finding it, and it helps them find the information easily in future.
Brilliantly organised teachers will have already written their plenary questions on to overhead transparencies when they plan the lesson, so they can spend maximum time examining pupils' written responses rather than frantically thinking up questions.
But to paraphrase the well-worn poster beloved of offices everywhere: the impossible we can do immediately; non-stop brilliance takes a little longer.
Tony Elston is head of modern languages at Urmston grammar school, Manchester