The report, A Marked Improvement?, by the University of Oxford and the charity, Education Endowment Foundation (EEF), says there needs to be more research into which marking strategies really work, but it also identifies some approaches that do make a difference.

The findings are largely based on a review of existing British and international academic literature. The researchers also analysed responses from nearly 1,400 teachers in over 1,000 primary and secondary schools for a survey commissioned by the EEF on 10 different marking strategies.

The report says previous research shows that teachers spend around nine hours a week on marking. Yet, it adds, time-intensive approaches such as triple impact marking , in which pupils respond in some way to the marking and the teacher then checks their later work, have not been properly tested. It also suggests that more research needs to compare the effects of ‘selective’ marking with the thorough approach – where teachers focus on spelling and grammar, as well as the content.

It says existing studies show that when pupils make careless mistakes, these should be marked differently to errors borne out of not understanding what was expected. The research also suggests that giving grades or scores can sometimes distract a pupil from the teacher’s written feedback, and that there should be more time set aside for pupils to digest the comments in order to learn from their mistakes.

The findings show that teachers need to know more about what works when they use written marking. Dr Victoria Elliott, Associate Professor of English and Literacy Education

Lead author of the study Dr Victoria Elliott, Associate Professor of English and Literacy Education from the Department of Education at the University of Oxford, said: 'The findings show that teachers need to know more about what works when they use written marking. It is clear that unless pupils understand and engage with the feedback, marking won’t lead to improvements in their work.'

The survey with teachers, conducted in November 2015, is the first to report back on marking practices, in particular. It shows that the most common strategy used by teachers is to write targets for improvement, with almost three-quarters (72%) reporting they did this on all or most pieces of work they marked. More than half of the teachers surveyed said they also identified and corrected errors on all or most pieces of work.

Co-author Professor Jo-Anne Baird, new Director of the Department of Education and former Director of the Oxford University Centre for Educational Assessment (OUCEA), said: 'We hope this report is the start of a conversation for teachers and researchers to consider the effectiveness and sustainability of different marking approaches.'

Sir Kevan Collins, Chief Executive of the Education Endowment Foundation, said: '‘Today’s report should be a real wake-up call for policymakers and school leaders. Why are we asking our teachers to spend hours and hours each week on time-consuming marking strategies when there is very little evidence to tell us which of these have any impact on pupil attainment? Rather than relentlessly pursuing unproven and unsustainable approaches, a guiding principle might be to mark less, but mark better, informed by what the evidence tells us so far is likely to have the most impact.'

Sir Peter Lampl, chairman of the Education Endowment Foundation, added: 'Smarter marking could save valuable teachers’ time while improving standards. This can make a real difference to how pupils learn and to teachers' workload.'