An extra hour spent in school per week is associated with a small improvement in GCSE outcomes, according to a report by the Education Policy Institute (EPI) published today.

This improvement is equivalent to around 0.017 grade points in each GCSE subject, according to the report commissioned by Law Family Educational Trust.

However, in response to this finding, the NAHT school leaders’ union warned that the identified gain is minimal and “unlikely to be the ‘game-changer’ the previous government implied it could be”.

A Department for Education White Paper, published by the previous Conservative government in 2022, set out an expectation that all state schools meet a requirement for a minimum of 32.5 hours of school time per week.

The EPI research shows that, overall, most schools are meeting or exceeding this expectation.

Just one-fifth of primary schools and a quarter of secondary schools that responded to the 2024 spring school census had school weeks shorter than 32.5 hours, the report says

The impact of a longer school week

The EPI analysis is based on attainment records in the national pupil database and school hours data derived from the 2024 and 2023 spring censuses. It is the first time this relationship between the two data sets has been studied in England.

However, the data did not allow researchers to understand how extra school time was being spent, and it raised questions about how some schools can deliver longer days, the report says.

“We recommend further investigation into how and why free schools can systematically deliver longer school weeks,” the researchers conclude.

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Researchers also conclude that there are benefits from setting out “clear expectations for schools on the length of school weeks”.

However, the report recommends further research into the type of activities undertaken during additional hours that lead to improved outcomes for pupils.

Languages subjects saw the most notable increase in attainment due to additional hours in school, according to the report, with an improvement of 0.063 points towards a GCSE grade.

However, researchers said this finding may have been influenced by a lack of comparable key stage 2 data and lower entry levels for languages GCSEs compared with other subjects.

Longer hours in school had slightly more of a positive impact on English and reading test scores than on maths test scores, the research shows.

Free schools have the longest week

Free schools have the longest school weeks overall, according to the report.

In 2023-24, free schools had nearly an additional hour of school time in primary and more than an hour in secondary per week compared with the average school.

This could be due to the “greater flexibility free schools have over their school days”, the EPI says.

Academically selective secondary schools also had longer school weeks - almost one hour longer than non-selective schools.

The school week also tended to be longer for schools rated “outstanding” by Ofsted and for those in London, according to the research.

“Outstanding” secondary schools had marginally longer average school weeks - over 20 minutes longer - than senior schools with lower Ofsted ratings.

Secondary schools in London had an additional half an hour of school time per week on average, compared with the national average. Schools in the East of England had an additional 20 minutes above the national average.

‘Unlikely to be a game-changer”

Ian Hartwright, head of policy at the NAHT school leaders’ union, said the report does not consider the “logistical challenges” involved with lengthening the school day.

These include increasing the hours of lunchtime supervisors and other support staff, and taking into account school bus times.

“We should be mindful that the gains identified in this particular piece of research are minimal, confirming that an extension of school hours is unlikely to be the ‘game-changer’ the previous government implied it could be,” Mr Hartwright said.

He described the previous government’s focus on longer school hours as “odd”, saying that there are a range of alternative policy options that policymakers should look at instead.

Pepe Di’Iasio, general secretary of the Association of School and College Leaders, said the Labour government’s policy of free breakfast clubs in primary schools “may offer a solution” in terms of longer school weeks. But he warned that they need to be “funded and staffed appropriately”.

The DfE has been contacted for comment.