CRITICS sometimes complain that the Government sees schools as production lines. Children join the conveyor belt in Year 1 move along to Year 6, transfer to a secondary, get on at Year 7 and are carried through to Year 11. As they pass, teachers stuff them with the national curriculum and try to meet test performance targets.

The Tories, judging by recent policy pronouncements, appear to see schools as islands. In an ideal world, they would like all schools to be independent, self-contained entities. Each school would be solely the responsibility of the island chief, with no overarching local administration. Accountability to the parents on each island would secure standards.

Our research shows that neither analogy reflects reality. However self managing they may be, state schools are elements in a system between which the “products” or “islanders” move. Moreover, the system itself is not self-contained. Children move between state and private schools and between countries. In the past 20 years, around 1.5 million children under 15 have flowed in and out of the UK.

In other words, some children join or leave the production line halfway through. Some get off to go abroad and come back again. Some jump from one line to another and can fall between the two. The more changes of school a child makes, the more opportunities there are for drop-out. And the greater the number of schools responsible for that child’s success or failure.

These facts are not just of academic interest. They are absolutely fundamental to strategies to raise achievement and to the role of the local education authority. This is why we embarked on our research. It is also why the Department for Education and Employment, recognising the significance of this issue, commissioned our interim report, published this week.

We have tried to build up a national overview of pupil “mobility”, or the proportion of a school’s roll that leaves or joins it in the course of a year. Below are findings from a postal survey of local education authorities, to which 87 per cent (130 out of 150) responded. Some responses were based on research and statistics, others on local perceptions. Overall, they are consistent with other evidence.

The survey sought to establish those factors associated with high levels of pupil mobility. Education authorities were asked which types of people were most likely to join or leave a school. They were also asked which housing situations and individualfamily situations were associated with a high pupil turnover.

Travellers, refugees, families moving for job reasons and the armed forces were the groups most frequently mentioned by authorities as contributing to high pupil turnover. More than half cited travellers, while about a third mentioned the next three groups.

When it came to housing, homeless families in temporary accommodation and families living in social housing were mentioned by more than half of the responding authorities. The majority who mentioned these were urban authorities; many of the other areas were in coastal resorts.

More than 40 per cent of authorities said pupils from women’s refuges would be likely to leave or join schools, and these authorities ranged from inner urban areas to coastal resorts and smaller towns and cities.

In the case of individual or family situations that contribute to high pupil mobility, a number of authorities stressed that they could only give anecdotal evidence, but the response was interesting. The most mentioned situation, cited by nearly two-thirds of authorities, was family breakdown or division. Authorities of all types and from all over the country said this was a factor.

The 67 (56 per cent) authorities who mentioned voluntary transfer (for whatever reason) between schools as contributing to high mobility were mostly in cities, as were the 42 authorities (35 per cent) mentioning permanent exclusions. Nearly a third linked children in care to high mobility, and more than 80 per cent of these were in the same urban areas.

London, other cities and conurbations, coastal resorts and the areas around armed forces’ bases were the principal locations of high-mobility schools.

However, the vast majority of authorities said that high mobility was an important obstacle to raising achievement in one or more primary schools (18 per cent said it was significant in 20 or more schools). Three quarters of authorities thought it was an issue in one or more secondaries.

Of 66 authorities providing data on a primary school that they considered to have high turnover, 10 identified a school with more than 70 per cent mobility in the course of a year.

This pupil mobility figure, used by many authorities, can be misleading. It adds the number of pupils joining a school to those replacing them, sometimes creating a false impression that, say, 90 per cent of pupils have left a class, when in fact about 45 per cent have left. But the highest pupil mobility rate in the study - 67 per cent - nevertheless paints an alarming picture of more than four pupils in every 10 leaving the school by the end of the year.

Around three-quarters of authorities said that high mobility had been raised with them as an issue by schools in connection with performance data, target-setting and funding. In more than half, it had been raised in connection with school improvement, taking excluded pupils and inspections. In more than 40 per cent, it had emerged in relation to special needs, attendance and other admissions issues.

We need to know much more about what pupil mobility means for local authorities and schools and what they need to do to ensure that children on the move don’t miss out. That is the next stage of our research.

A research project on pupil mobility in schools, funded by the Nuffield

Foundation and the Department for Education amp; Employment, is being carried out by Dr Janet Dobson and Kirsty Henthorne at the migration research unit, department of geography, University College London, 26 Bedford Way, LONDON. WC1H 0AP. Tel: 020 7679 7568 or 020 7679 5427; fax 020 7679 7565.

Their interim report, Pupil Mobility in Schools, is available from the Department for Education and Employment publications centre, PO Box 5050, Sherwood Park, Nottingham NG15 ODJ. Price pound;4.95 A four-page research brief is available for free PUPIL MOBILITY IN SCHOOLS

Groups mentioned by local education authorities as likely to join or leave a school

* Travellers

* Refugees

* Children from: Homeless families in temporary accommodation

Families in women’s refuges

Families suffering breakdown

Armed forces families

Families moving for job reasons

* Children in care

* Excluded pupils

* Pupils changing schools voluntarily ‘Three quarters of authorities thought pupil mobility was an issue in

one or more secondaries’