Mixed-age classes, where children of different year groups are taught together, are fairly common. All local authorities have schools that operate them.

Government statistics from 2002 show that around one-third of primary classes are mixed age.

There are two main reasons for the approach: economic necessity or a belief that such teaching is better for pupils. But studies of mixed-age classes in primary schools have shown that they are almost always introduced through economic necessity.

In 1983, Neville Bennett, then professor of educational research at the University of Lancaster, found that 70 per cent of those operating mixed-age classes did so for this reason.

For this reason, mixed-age classes are often seen as a compromise and parents can, and do, object.

Gill Heslop, head of Easington Lane Primary in Sunderland, had to introduce mixed-aged classes 10 years ago when her pupil numbers fell below a viable level.

“There were problems in the beginning, particularly with parents.” she says. “We had to reassure them that no matter where their child was, they would get the education and curriculum they needed.

“They think the classes change from year to year and couldn’t accept that their child would be in the same class the following year.”

Mark Purcell, head at St Clare’s Catholic School in Preston, which has a mixed receptionYear 1 class and a mixed Y1Y2 class, said: “We have an induction evening in June where I talk to parents and fill them in on what takes place.

“Parents can be concerned about their children going into the mixed receptionY1 class because their children are just starting school.

“I ask the parents of the children from the previous year to talk to the new ones. It’s easy for me to say it is fine, but it works better if parents who have lived through it can let the others know what it’s like.”

Parents’ concerns usually stem from the belief that their child is being held back, or worries about younger pupils being isolated. But there is little evidence that children are disadvantaged academically by mixed-age classes.

Advocates of the approach believe it is beneficial. They say pupils develop cognitively and socially through mixing with older and younger children. Older children in particular can benefit from becoming “experts” and explaining things to the younger ones.

There is also the advantage that older children who are below average for their age do not have to feel a failure in a mixed group.

Valerie Wilson, former director of the Scottish Council for Research in Education at the University of Glasgow, reviewed all the studies on mixed age - also known as composite classes - in 2003. She concluded that the evidence was equivocal: there was no proof that mixed-age groups adversely affected pupils’ performance, but evidence did exist that they could gain socially.

Colin Richards, emeritus professor at the University of Cumbria, said: “There is no evidence that mixed-age groups per se result in lower attainment. There is evidence that mixed-age classes, particularly when the groups are small - around 20 to 24 children - do have a positive social advantage.

“The real problem is if there are 35 pupils-plus in a mixed-age group. Then there are probably no social advantages.”

But it is not only parents who need to be won round. Teachers may also be worried about moving to mixed-age classes with more complex lesson plans.

Professor Richards said: “Teachers facing it for the first time will find it more difficult to organise.”

Once the decision to have mixed-age groups is made, there is then the question of how to organise it.

A study of schools in one London borough by Dr Chris Berry, then at the Institute of Education, found that the most common ways of assigning pupils were by ability and by age, so the oldest pupils in Y1 were in the same class as the youngest in Y2. This also had the advantage of ensuring summer-born children were not always the youngest in their class.

But grouping by age was already in place when Mr Purcell arrived at St Clare’s six years ago. “I arrived in April and inherited the system,” he said. “The next year the 12 oldest children starting school happened to all be girls. It was a nightmare: they didn’t necessarily get on and the range of abilities was immense.”

Now the school assesses children during their first two weeks in reception, when they attend part-time. They are then assigned to either reception-only or the mixed receptionY1 class, largely by ability but also taking parental preference and friendship groups into account.

MAKE IT WORK FOR YOU

- Talk to parents. Involve other parents if possible.

- Recognise teachers will need extra support in planning.

- Decide your rationale for grouping pupils. What works well in one school will not necessarily be best for you.

- But keep class lists flexible: allow children to move if they are not getting on with their new classmates.

- Mixed-age classes mean new classmates each year. Get a programme going to help instil teamwork for the children - and their teacher.