It is more complex because every school year in France has multiple ages, as seen in table 1 page 91, and page 103.
Because they start at different age even in their Reception (page 69, table 1 bottom).
Some students entered Bac early at 14, 15, 16, 17, and also at 19, 20 and older. It is the legacy, which they are phasing out fast (page 103). Number of repeats fallen sharply to 0.4-2,2% from 9% in 2005.
Most able can go faster. Less able can catch up, but nobody is left outside in the cold.
The real answer to what they did to improve outcomes is in primary school, at the entry, at the age of 6 and 7. They delayed entry in primary for some.
The “policy of fluidity of trajectory” reduced the falling behind in Primary school drastically, which benefited the most socially advantaged and the most disadvantaged.
Five years after starting their first primary year (CP), 91% are in year CM2 as expected,
1% skipped a year forward and are a year ahead, 7.6% are behind, 0.2% are in Special schools or 2 years behind (Page 77. Table 1).
Graph 2 shows most of the falling behind is at the age of 6 and 7 in CP, CE1.
They reduced falling behind sharply illustrated by the cohorts of 2011 vs 1997.
The percentage of children who started secondary school at expected age is 92% in 2017, a sharp increase vs 82% in 2005. Those who are 1 year ‘late’ are 7.6%, a sharp reduction from 17% in 2005. (Table 1, page 75)
The percentage of children who don’t repeat years has increased (Table 3, p 77) for children of:
Senior Managers, Professions, businessmen: from 89.8% to 96.4% (+6%)
Unqualified manual workers: from 66.6% to 86.7% (+20)
Unemployed who were never employed: from 57.6% to 75.7% (+18)
But they claim they reduced this unemployed statistic drastically by 3.5% in just one last year.
These 7.6% being 1 year behind in Primary could be dealt with good intervention, SEN or otherwise, to remove repeating all together.
Whatever it was, their new policy improved outcomes for the disadvantaged and helped the advantaged as well. The most able started primary earlier and skipped a year forward if necessary.
What actually happened it seems is that they set as it were at the entry to primary school. They keep them in early years until they reach the milestones and are ready (page 68). The most able can start early. The whole school year is a set. Table shows children starting their CP at the age of 4, 5, 6 (the nominal age) or 7 etc. (page 69, table 1 bottom, column 2,3,5). It gives numbers of children by age from 4 to 11 in Preelementary and in Elementary (=primary)). There is huge overlap starting from 4 years old, staged entry. So every school year has multiple ages up until their year 12.
The difference is made in early years and Infant school.