The £55 million Nottingham academy which opens today

It opens for students today despite warnings over the impact of large schools on pupil discipline.

A teaching union has called for size limits to be imposed on schools after conducting a survey which drew a link between pupil numbers and bullying.

The Association of Teachers and Lecturers claimed big comprehensives were turning into 'factories' and warned pupils too often missed out on assemblies and sports days.

The chief executive of Nottingham Academy, Barry Day, said students would be split into three 'schools within a school' each with their own head teacher and staff.

These schools would be further subdivided into units of no more than 400 children in a bid to give pupils and parents a traditional school experience. 

Mr Day was until now head of Greenwood Dale, a Nottingham comprehensive which has been lauded by Ofsted for achieving impressive academic results with youngsters from deprived backgrounds.

A view of the academy which has been created by merging three schools

That school is effectively taking over a nearby primary and struggling secondary - the first time a head teacher has taken advantage of new Government rules allowing high-performing schools to sponsor a semi-private flagship academy.

Mr Day said it was important to allow popular schools such as Greenwood Dale to expand.

'Parents want a good education for their children. We will now be able to offer places to all those students we couldn't take before because of oversubscription,' he said.

Today the academy opens on the sites of its three predecessor schools, catering for more than 2,200 students.

It is expected to open in its state-of-the-art new buildings on these sites over the next two to three years, when it will accept 3,600.

Among the academy's innovations is that most pupils will be expected to take GCSEs a year early, at the age of 15, allowing for a three-year run-up to A-levels.

Mr Day says this will boost students' chances of getting into good universities.

Simon Richey, education director for the Gulbenkian Foundation, a charity which supports large schools to subdivide into smaller units, welcomed the academy's structure.

'It's very hard for pupils to have any sense of allegiance in very large institutions. It is very difficult for them to know the teachers who teach them. Those things are critical if children are going to learn well,' he said.

Labour will today deploy 19 ministers - including nine Cabinet ministers - to visit new schools around the country, among them Nottingham Academy.

It will announce it has reached its target to build 200 new flagship academies - 'independent' schools funded by the state - a year early, with the opening this September alone of 67.