In the old days it seemed so simple. There were state schools, split into grammar and comprehensive, and there were private schools.

Now the education system can seem a bewildering mix, with terms like community school, trust school, free school, all-through school, cluster and academy added to new relationships between different tiers of the education system, from nursery to university. But in Norfolk today, one area is changing faster than any – academies.

Originally a Labour innovation targeted at failing schools in deprived areas, the coalition government expanded the programme to all schools. They are all-ability schools within the state system, but become independent of the local authority and gain greater freedom over their curriculum, finances and teachers' pay.

Academies can be divided into three categories: sponsored academies, usually poorly-performing schools put under a sponsor from the world of education, business, faith or the voluntary sector; converter academies, usually successful schools allowed to stand alone and run their own affairs; and free schools, newly-formed institutions set up with public money but independent of the local authority.

According to the latest government figures, Norfolk now has 36 academies, and it is a growing trend, with five converting in 2010, compared to 12 last year and seven so far this year.

It is largely a secondary schools phenomenon, with 22 of the 51 in the county having converted, and another two awaiting final approval.

Just 10 of Norfolk's more than 350 primary schools have made the same change, with four more applications nearing completion.

For some schools, becoming an academy is the end of the story as far as organisational change is concerned.

Reepham High principal Mark Farrar said the decision was a 'purely pragmatic' one designed to avoid a £250,000 cut in income, and he said the school, as intended, had not changed in any significant way as a result.

He said: 'We have no intention of joining an academy chain. Reepham High School and College values its independence and the flexibilty that this brings. However, we are committed to continue to work collaboratively with all Norfolk schools, be they stand-alone academies, academies in a chain or local authority schools.'

But other schools which have left or are leaving County Hall control are now seeking other, alternative, organisations to join instead.

Schools looking for a sponsor often turned to national chains, such as the Birmingham-based Ormiston Trust, which took on Costessey and Oriel High Schools in 2010, renamed them Victory and Venture, and saw them achieve 'outstanding' Ofsted inspections recently, or the Academy Transformation Trust, which has a cluster of schools in west Norfolk.

An Ormiston spokesman said: 'The advantages of being part of a trust the size of Ormiston is the added capacity to provide the 'back office' support and services we can offer. Academies have access to national experts and a wider package of support.

'It also means there are opportunities to have a deep and meaningful collaboration across geographic borders. For example, Ormiston Venture Academy first drew support from schools as far away as Stoke on Trent.'

She said the trust had plans to expand modestly, and may add 'a couple' of schools near its existing academies in the area.

However, some national chains have seen their plans to expand blocked by the government over concerns they do not have the capacity to support all their new schools.

The Hewett School in Norwich chose the national chain the Academies Enterprise Trust (AET) after examining how much support each chain could give it, their professional development of teachers, their record of securing government capital funding, and whether they would change the school's name, uniform or ethos.

However, the government withdrew its initial approval to join AET, and senior associate headteacher Rob Anthony said the school was happy to remain a foundation trust school rather than go with any other group, national or local.

But now there is a growing trend for Norfolk schools to choose Norfolk support, with three groups who say they intend to remain local making the running.

The Inspiration Trust, under chief executive Rachel De Souza, will include two free schools, the Sir Isaac Newton Sixth Form and Jane Austen College, in its portfolio, while the Transforming Education in Norfolk Group (TEN), includes City College Norwich, a 14,000-student further education institution, as well as high schools.

And in March, the Diocese of Norwich won government approval to become an academy sponsor through its Diocese of Norwich Education and Academies Trust, and is currently advertising for two posts starting in September as it develops and grows.

Cromer Academy, a relatively small high school, became a converter academy in 2011, and in May decided to become part of a bigger organisation and joined the Inspiration Trust.

Headteacher Penny Bignell said: 'We are joining a larger group because we want to expand opportunities for students and staff – more choice of subjects, links with the Norfolk and Norwich University Hospital, links with universities to continue to raise aspirations, staff development and working with other staff across the trust to improve practice.

'There will be access to funds for identified projects which we do not have at present. As a small school we believe joining Inspiration will help secure our future in Cromer.

'The Inspiration Trust is a Norfolk-based trust, which is appealing, so we can work with other schools across the trust. It is also planning to stay small with eight to 10 schools, which governors felt would be beneficial to us.'

Meanwhile, Fakenham High School has ministerial approval in principle to become a sponsored academy under TEN, and governors at Attleborough High School unanimously decided to become an academy within the same group.

Dick Palmer, chief executive of TEN, said: 'Norfolk has its own solutions to its own problems and I think through organisations like TEN we can show the Department for Education that Norfolk can resolve its own problems.'

And what about the future?

Academies and free schools look set to be a permanent part of the education landscape whoever wins the next election, and Labour's Stephen Twigg has proposed giving all schools the freedoms academies currently enjoy, although with greater community involvement.

Education minister and Conservative South West Norfolk MP Elizabeth Truss said: 'I think one of the things there may be is a trend for more all-through academies, with primaries linked to the local secondary and also schools reaching down the age range into the early years. I think there are a lot of different models.'