Yet Britain is exceptional in this, argues Professor Dylan Wiliam of King's College London: in fact all of the countries which score higher in international comparisons than us teach secondary children in mixed-ability groups.
In a new study involving questionnaires to more than 2,000 secondary children and teaching observations in six schools, Wiliam and fellow academics Jo Boaler and Margaret Brown, believe they may have discovered why setting and poor performance go hand-in-hand.
Setting is deeply unpopular with the children in the study, all of whom moved from mixed-ability groups in Year 7 to being set by ability in Years 8 or 9. Forty of 48 students interviewed by the researchers from setted classes wanted either to go back to mixed-ability groups or to change sets.
Interestingly, top and bottom sets were almost equally disillusioned: in one school every one of the eight girls interviewed from set one wanted to move down; so did six out of eight boys.
The reason for their unhappiness, argues Professor Wiliam, is that the same teachers who were perfectly capable of gearing their teaching to suit children at different stages inmaths when they were teaching Year 7 mixed-ability classes, completely changed the way they taught once they were faced with ability sets.
They treated the top set as mini-mathematicians, racing through the syllabus and telling any child who said they did not understand that they should understand because they were in the top set.
At the same time, children in the bottom set found teachers hugely reduced their demands, often only requiring them to copy down examples from the board and not do any working out at all.
Going over to setting does not mean teaching methods need change at all, says Wiliam, particularly as there is no reason why a "top" set should be very able - since it only comprises the 30 best mathematicians in a year of that particular school.
But, in practice, teachers assume they can change to a much less demanding teaching style, even though the effect on children is utter disillusionment:
"There is no doubt in my mind that the atmosphere in top-set classrooms, the lack of time to really think through and understand what you are doing, means that half the students who would potentially be the best mathematicians give it up."
"Students' Experience of Ability Grouping" will be published in the December issue of the British Educational Research Journal