In 1999, Ofsted put St John’s primary into special measures. Although teachers were described as “diligent, hard-working and committed to securing improvement”, inspectors said the Birmingham inner-city school was “failing to give its pupils an acceptable standard of education”.

So what was the problem? Three out of four children at St John’s are on free school meals, and one in four has special needs. But the main difficulty is the high mobility of the local population. Headteacher Sandra Bailey, while working with HMI to pull the school out of special measures last year, was furious about the inflexibility of a system that landed her in a waking nightmare. “They weren’t interested in our mobility figures,” she said at the time.“Only in the attainment statistics. But what control do we have over what underpins those statistics?”

Family mobility is a normal part of an industrial society - more than one million children counted in the last census had moved in the previous 12 months, and almost one child in 10 moves each year. Primary-age children move less than pre-schoolers, and secondary-age children move less than primary. Travellers, refugees, work-related movers and armed forces families are the groups cited by local authorities as being responsible for most pupil mobility.

Much of this movement is predictable and planned, but many authorities have identified family breakdown as a cause of mobility. And it is this group that often leads to the most chaotic situations, where children become the victims of multiple transfers from one area to another, one school to the next. It’s called turbulence, an appropriate name for a phenomenon that can cause chaos in schools. In inner-city areas it can produce classes that change from week to week; Birmingham education authority has an average mobility rate - children who start or leave schools other than at the normal transfer times - of around 20 per cent a year. And rates for individual schools can be more than 80 per cent. In a class of 30, 24 will move in or out in one year.

Research in the London borough of Hackney shows that mobile pupils - the new arrivals - are more disadvantaged than the general school population; more likely to be eligible for free school meals; more likely to have English as a second language; and more likely to be boys. SATs scores reflect these problems.

Lower scores focus attention on the schools with high mobility rates, but not necessarily in the way they would wish. “I now realise that I didn’t have the data to combat the raw evidence of national tests,” says Sandra Bailey. “After the shock, I started to gather evidence. The effect of mobility had to be pinned down and understood without becoming an excuse for low expectations.” The school now keeps separate statistics for the “core” of children who stay from year to year. “By comparing those figures with the whole group, we can put bald results into a context,” she says, “demonstrating pupil progress and illustrating the effect of pupil mobility.”

But Ms Bailey remains unhappy about the way Ofsted treats schools with high mobility. “Mobility changes the balance and dynamics of a class,” she says. “It doesn’t just affect the children who have moved.”

St John’s came out of special measures last November. Ms Bailey has moved on to a bigger - and less turbulent - school in the north of the city. St John’s governors will soon be advertising for a replacement and, in the meantime, Olga Owen, an experienced Birmingham primary head, is looking after the school. Mobility figures are still daunting, but the staff are confident that the problem is manageable.

On the move

Various methods are used to gauge pupil mobility. One of the more common measures is the ‘joiners plus leavers’ formulae (JPL): JPL = pupils joining school + pupils leaving school x 100 divided by the total school roll.

Percentages above 15 represent significant mobility; St John’s had figures that ranged from 35 per cent to 59 per cent.

Last year, St John’s key stage 1 results showed that pupils were performing to national expectations and the level 4 key stage 2 performance had improved significantly, especially, but not only, for the “core group”. The 2002 results are expected to show further improvement.

2000 2001

English

All pupils 37% 55%

Core group 53% 73%

Maths

All pupils 43% 50%

Core group 53% 64%

Science

All pupils 49% 64%

Core group 60% 73%