This year-long pilot was set up by education minister Francois Bayrou. Soon after taking office nearly two years ago he pinpointed the coll ge (lower secondary) as the "weak link in the educational system" and in urgent need of reform. Too many pupils, he said, arrived at their coll ge with problems including a lack of basic skills, notably reading, which would inevitably lead to failure in all subjects.
Pupils "in difficulty" are defined as those who have repeated one or two years at primary school, whose tests reveal problems in French, maths or both, or who are below a certain standard after the first two years at coll ge.
The education ministry estimates that about 10 per cent of pupils are in "great difficulty", with all three characteristics, while another 15 per cent have two. These children tend to come from disadvantaged homes and their parents are more likely to be single, unemployed or unqualified.
The test schools - 310 public, plus 58 from the independent but state-subsidised Catholic sector - represent a mixture of areas and social background and some were already using some of the methods envisaged. The experiment is taking place in the first year of secondary education when most pupils are 11.
The schools must follow certain rules. A slightly longer week gives teachers greater opportunity to split classes into smaller groups and to try new ideas. Hours devoted to French and physical education have been increased, and civic instruction is spread across subjects other than just history. Three hours a week of compulsory supervised study periods are aimed at pupils who have problems working at home.
But within the guidelines, schools are free to try anything. Jacques Arnoux, head of Coll ge Benjamin Franklin in Epone, 50 kilometres from Paris, claims "there are 368 different reforms being carried out in this experiment".
He chose five subjects for the trial - French, maths, English, historygeographycivics and PE - but he laid the groundwork while the pupils were still at primary school, asking their teachers to detail their strengths and weaknesses, any disruptive combinations of children, and friends who would be happier kept together. With information on individual pupils, he could build up a profile of the new intake and divide the pupils most effectively between the seven forms. A complicated formula avoids creating a "slow" stream and prevents too wide an ability range in any one class.
Remedial lessons at Benjamin Franklin also teach pupils techniques to help them study - research shows that those in difficulty are not aware of learning methods - and Dominique Brun, co-ordinator of the English project, has introduced a "how to behave" element to deal with disruptive children.
At Coll ge Rodin in Paris, head Anny Duchesne-Merigot has concentrated on French and maths. During maths, for example, 11 pupils leave their usual classes to join a remedial group. They study the full national programme but use methods and work at a pace suited to their requirements.
Their teacher, Anne Marie Tolla, takes them through a variety of exercises. Meanwhile, their mainstream schoolmates are also doing maths, the simultaneous schedule allowing pupils from either group to switch to the other according to their needs and progress.
As well as the extra study sessions, Rodin pupils attend an hour's weekly workshop, in activities such as drama, computers, reading and Scrabble. Andre Agra, principal education adviser who has been running them for years, says they are a great help for developing the interests and skills of children with problems.
The reforms depend on the co-operation of teachers, who often have to take on extra duties. They also mean a greater emphasis on teamwork for a teaching force that traditionally enjoys a large measure of classroom autonomy.
Some teachers' representatives are worried about what will happen when the reforms become universal next year. According to Francoise Dumont of SNES, the biggest secondary teachers' union, the 1,000 new teaching posts promised will not be enough to ensure success. She also criticises the tight schedule.
SNES's greatest concern is the loss of a structured timetable. "Some subjects are under threat, technology, for example, in favour of the increased French and maths," says Mme Dumont.