All pupils will be able to gain at least a grade C in GCSE maths for the first time under reforms unveiled this week.

The Qualifications and Curriculum Authority announced that an existing three-tier system, in which pupils sitting the lowest paper have no chance of gaining a top grade, will be scrapped in favour of a two-tier model.

The move, being phased in from September, will eradicate an anomaly that allows pupils taking the top paper to gain an A grade, even if they score fewer than half-marks.

It is said the reforms will bring maths more in line with other subjects that already operate on a two-tier system.

However, critics say the changes have been rushed through because they were tested for the first time this summer and that they fail to address lingering concerns over standards.

Doug French, president designate of the Mathematics Association, said:

“They are absurdly foolish to embark on something as radical as this without properly considering the consequences.

“It is difficult to see how the decision will improve the current three-tier situation, problematic though that is. It may have the effect of boosting the number of grade Cs, but that is not the same thing as really raising the standards of mathematical education for all students.”

GCSE maths has traditionally been offered in three tiers - foundation, which covers grades D to G, intermediate (B to E) and higher (A* to C).

In 2004, a government-backed inquiry concluded that universities and employers had lost faith in the quality of GCSE and A-level maths. It found that schools with an eye on league tables were taking tactical decisions to put pupils into the second most difficult paper because they saw a grade B as easier to get than in the top-tier test. Pupils’ morale also suffered if they were denied the chance to gain at least a grade C.

For the past three years, the OCR exam board has trialled its own two-tier GCSE in which all pupils can achieve a grade C.

However, the exam attracted controversy last year after it emerged that pupils could gain a B with just 17 per cent on the top paper, and an A with 45 per cent.

Traditional three-tier exams have been under fire for similar reasons.

Academics from London university’s institute of education were asked to evaluate the OCR pilot scheme as well as a separate two-tier model, drawn up jointly by OCR and the exam boards AQA, Edexcel and the Welsh Joint Education Committee.

The second model was tested on 430 students this summer. According to the institute of education’s report, more students favoured the second trial, which offered a broader range of more accessible questions.

The QCA will now adopt the second model. It will require teachers to place pupils in one of two tiers - a higher paper covering grades A* to D or the foundation tier covering grades C to G.

It will not require any curriculum changes and will see pupils sit new-style exams in summer 2008 after starting GCSE courses this September.

A QCA spokeswoman said: “The standard two-tier model will ensure fuller teaching of the whole mathematics curriculum and motivate and engage less able pupils to demonstrate their best performance in the examination.”

* graeme.paton@tes.co.uk