Children are making virtually no progress in mathematics in the first three years of secondary education, a major study showed yesterday.
Many pupils make almost no progress in maths in the first three years of secondary education.
Even the brightest pupils struggle between the ages of 11 and 14 as they "plateau" after leaving primary school.
Some children may even be going backwards - raising fresh concerns over the way they are taught.
Academics from Manchester University said there were "short-term" increases in children's maths skills as they took national tests at the end of primary school but many regressed after the exam.
The claims come only 24 hours after figures showed that almost one in four 11-year-olds failed to reach the standards expected of them in maths this year.
The latest report will pile fresh pressure on ministers following the publication of a report showing that Britain had fallen in a worldwide league table for teenagers' maths skills.
Fifteen-year-olds were ranked 24th in the world in the study by the Organisation for Economic Co-operation and Development - below the international average.
Manchester researchers devised independent maths tests to measure the performance of 12,591 pupils aged between five and 14.
Professor Julian Williams, the project leader from Manchester's school of education, said: "Children across a range of abilities make practically no progress in maths between the ages of about 11 and 14.
"We did record short-term improvements in test scores around the period of national testing at Key Stage 1 and 2 [seven and 11-year-olds]. However, these increases were short term … suggesting lack of lasting gain in children's understanding.
"Policy makers should, as a matter of urgency, seek to survey performance by large-scale representative samples."
The research paper identified a "plateau" effect during the first years of secondary schooling.
The paper said that progress was "very slow over this period" suggesting that "the repeated exposure to the same curriculum in secondary school has a negative effect".
The report adds weight to growing fears that pupils' abilities are being wasted in the first few years of secondary education.
Earlier this year, the Tories compared recent results gained at the age of 11 with those gained at age 14.
They found that almost 150,000 pupils made no progress in science, while 85,000 failed to improve their grades in English and 30,000 in maths.
They said that the problem was due to the number of mixed ability classes in secondary schools.
The Department for Children, Schools and Families described the study as a "small sample", insisting that "independently audited national tests" taken by 600,000 pupils every year showed clear improvement since 1997.
A spokesman said it was working on a review of maths teaching that would be "seeking evidence from experts in early development and maths education".
