Pupils make virtually no progress at maths in their first three years of secondary school, a study by Manchester University has found.
Professor Julian Williams, who lead the research, accused schools of "teaching for the tests" rather than challenging children.
"Progress is much slower than anyone would have thought," he said. "The results are no better for higher achievers than for lower."
Professor Williams and his team tested more than 12,000 primary and secondary children at 111 schools. While the primary pupils improved every year at maths, secondary students aged 11 to 14 made practically no progress.
"People have talked about a `plateau effect' at secondary school, but we have actually measured it," Professor Williams said. "We need a way of teaching which is based on challenging students, rather than practising their performance for tests."
He called on the Government to carry out rigorous, national surveys of children's achievement in maths so that policymakers knew what was really happening.
Lucy Wenham, an advanced skills maths teacher at Uxbridge High School in Middlesex, said the secondary maths strategy was often implemented in a prescriptive way which encouraged key stage test-style lessons. "There is also a tendency, in the name of variety, for lessons to jump from one topic to another without consolidating basic skills," she said. "Children need regular routines and practice to embed their knowledge."
Peter Hall, general council member of the Association of Teachers of Mathematics and an AST at Imberhorne School in East Grinstead, West Sussex, said most students there improved by two national curriculum levels in their first three years. "The content at Level 6 is a lot harder than Level 4," he said. "Students have made huge progress if they can understand the Level 6 work in Year 9. There are many abstract concepts - such as algebraic manipulation." He praised the work of primary schools in improving levels of numeracy.
But Tony Gardiner, reader in maths at Birmingham University and past president of the ATM, said primary school teaching had eliminated real maths in favour of short-term skills.
"Everything you could call mathematical is ignored at primary school," he said. "Children are being pushed down a dead end. They are not able to recover at secondary school because teachers' hands are tied by the Sats."
Mr Gardiner compared key stage tests to a photograph taken from a flattering angle. "As soon as the children are involved in independent tests, they're stuffed," he said.
A spokesman for the Department for Children, Schools and Families said that key stage test results in maths over the past 10 years showed clear improvement by children of all ages.