Teachers must do more to make girls believe they can do well in maths if they want to close a stubborn gender gap in the subject that persists in the UK and across most of the developed world, according to a new report.

The recommendation comes in a new report analysing data and test results collected from more than 60 different territories for Pisa (the Programme for International Student Assessment) to discover why boys and girls do not perform at the same level.

It concludes that the gap is explained by differing levels of confidence and expectations rather than innate ability or aptitude. 

“The gender gap in mathematics performance mirrors the gender gap in students’ drive, motivation and self-beliefs,” the report says. 

“Given girls’ lower levels of confidence in their own abilities, school systems, teachers and parents should try to find - or create - more effective ways of bolstering girls’ beliefs in their own abilities in mathematics, both at school and at home.”

The study shows that across developed Organisation for Economic Co-operation and Development (OECD) countries 15 per cent of boys were able to tackle the most difficult maths questions in the Pisa 2012 test; in comparison, only 11 per cent of girls were able to reach the same level.

In the UK, there is a similar gap: 13 per cent for boys but only 10 per cent of girls could answer the most difficult maths questions. Results from Shanghai are provided as an example of why this need not be the case. Boys in the top-performing Chinese city still outperform girls in maths, but only slightly.

And the stellar performance of the average 15-year-old girl in Shanghai busts any myth of innate female inferiority in maths, with a test score of 610 that is “well above boys’ average performance in every other country and school system that participated in Pisa”.

It is also well above the average girls’ score of 488 in the UK - the equivalent of three years at school.

Francesca Borgonovi, the OECD author of the report, said: “Most of the [high performing] Asian countries have a very small gender gap and they have lower average socioeconomic disparities [in student achievement].

“So where an education system really promotes learning opportunities for all… they are capable of delivering on all fronts. They believe in the abilities of all children and are able to capitalise on those.”

The UK has a much bigger maths gender gap among poorer performers than the OECD average, because the country’s lowest-achieving girls do particularly badly in the subject.

The report focuses on maths but notes that the gender gap is reversed for reading, where “girls outperform boys… in all countries and economies by the equivalent of one year of school”.

In maths, the difference between the genders feeds through to 15-year-olds’ future plans, with only 38 per cent of girls planning to pursue a career involving a lot of maths, compared to 53 per cent of boys.

The report warns that such low expectations of success in the subject are self-fulfilling and that “unless girls believe that they can achieve at the highest levels, they will not be able to do so”.

In the short term, it suggests that “changing these mindsets may require making mathematics more interesting to girls, identifying and eliminating gender stereotypes in textbooks, promoting female role models and using learning materials that appeal to girls”.

In the long term, it calls for a “concerted effort” from parents, teachers and “society as a whole” to tackle a gender gap that it says has “remained stable since 2003 in most countries”.

The small number of exceptions where girls outperform boys in maths - Iceland, Jordan, Malaysia, Qatar and Thailand - were presented as further proof that gender differences were determined by culture rather than ability.

Andreas Schleicher, OECD deputy education director, said: “It is a lot to do with the expectations and attitudes that young people have. There seems to be a pretty close relationship between what young people expect for themselves and their performance.”