Good feedback is at the heart of effective teaching. Some studies have suggested that feedback can boost the learning of pupils by an incredible eight months during one academic year. Recent trials in busy everyday classrooms suggest that more realistic gains of three to four months are achievable.

If it’s so effective, then why is it not done more often? Because feedback is deceptively hard to deliver consistently well in the classroom; it’s easy to slip into generic observations that don’t address specific misunderstandings or knowledge gaps.

Educational researcher John Hattie claims that 40-50 per cent of what teachers teach, children already know. Meanwhile, teacher talk typically takes up more than 60 per cent of classroom time. So you can appreciate how more effective feedback would make a big difference.

So what do teachers need to think about?

Feedback can be given at four levels. The first three are about the learning activity itself (how well-written an essay is, for example); the learning strategies used (such as planning and reviewing a piece of work); and how pupils manage or regulate their learning (for example, when to seek feedback if you are stuck). Feedback at these higher levels can have a lasting effect on learners.

Finally, feedback can be about students as individuals (such as saying, “What a clever girl”). This should mostly be avoided: it doesn’t offer next steps for learning and implies that no effort is required to improve.

What works best?

Research suggests that feedback is most effective when it is specific, accurate and contains clear steps for what to do next. It can be verbal, written or given through tests. It should not be too detailed, as you don’t want to do all the work for the learner.

A key consideration for the teacher is to engage in timely, “on the go” formative assessment in the classroom. One of the problems with structured programmes, such as Assessment for Learning, is that they can be implemented like a formula, drifting into summative tick-box assessment with little benefit for learners, or becoming so routine that they don’t engage learners - or teachers - in making effective judgements.

What else should teachers consider?

Try to find a balance of suitably challenging but sparing feedback. Look for the impact of feedback on pupils’ behaviour. How has it been received and understood? Focus on quality, not quantity, of marking and suggest steps for future learning in the comments. And remember, feedback can come from peers as well as adults.

Lee Elliot Major is chief executive of the Sutton Trust and Steve Higgins is a professor of education at Durham University. Together, they authored the teaching and learning toolkit, now the Education Endowment Foundation toolkit