GCSE reforms that will replace lettered grades with numbers, end controlled assessments and modular courses, and revamp English and maths exams have received a mixed reception in the region.

South West Norfolk MP and education minister Elizabeth Truss hailed the announcement by the exam regulator Ofqual, but some headteachers said the changes would leave students with fewer opportunities to demonstrate their range of skills.

David Brunton, principal of City Academy Norwich, said the introduction of nine grades, instead of the current eight, would push the brightest students, which he supported.

However, he added: 'Whether changing from letters to numbers is the best way to do it, time will tell.

'There will be people in Wales who will still be getting As, Bs and Cs. I don't know whether that will help employers or hinder them. I think the concept of As and A*s is pretty well known, so from the employers' point of view, more than the higher education point of view, what 'nine' actually means will take a little getting used to.'

However, he said cutting coursework was a 'retrograde step', and that concerns about parents helping children had been largely addressed by having controlled assessments at school.

He added: 'It took a lot of years to move away from the singular form of assessment, and the idea was that it allows people to show different abilities and skills more suited to the world of work. It's rare that a person has to swot something up and write it up for two hours, without reference to anything else, at work.'

Rob Anthony, associate headteacher of the Hewett School in Norwich, described the reforms as 'mixed', and said: 'This is more change, yet again. Every single year group for the next four or five years are having something slightly different to contend with, and that's a problem for schools because we have to work out what we can and can't do, and it's different for every year group.'

He also warned that girls could be disadvantaged by the removal of coursework.

He said: 'One of the reasons coursework was brought in was that girls did not do as well in terminal exams. Generally, girls work best over the time of the course, and they do worry about exams far more than boys.'

Teenagers will have to study at least 15 poems at GCSE, including works by authors such as Wordsworth, Byron and Keats, under a major shake-up of the exams.

In future, pupils taking GCSE English literature will be required to learn poems by no fewer than five poets - and to study 300 lines of poetry at a minimum.

Ms Truss said: 'It is vital that children leave school with a full understanding of English language, literature and maths. The focus on English and mathematics is key as both subjects are critical to learning and form the foundation for studying other disciplines.

'The next GSCE mathematics will command a deeper and broader understanding with greater emphasis on ratio, proportion and rates of change. It is anticipated that schools will increase teaching time on maths, which is currently lower than in other countries.'

Chris Keates, general secretary of the NASUWT, the largest teachers' union, said: 'These changes are being rushed through at breakneck speed, driven on by a political imperative, rather than the needs of pupils.

'Particularly worrying is that there is no time to pilot of any of these proposals to test their effectiveness or their impact on student attainment.

'This approach also risks imposing on schools a qualifications system that could create massive bureaucratic and workload burdens that distract teachers and school leaders from their core responsibilities for teaching and leading learning. This could have profoundly negative consequences for students.

'The government has tried consistently to portray GCSEs as broken qualifications. The fact is, however, that the GCSE has proved itself to be a robust and reliable qualification which is highly valued by pupils, parents and employers.'