Methodology
A stratified sample of 45 mixed gender secondary comprehensive schools was
selected for the study, representing a range of grouping practices, intake and location
spreading from London and the Southern counties of England to East Anglia and
South Yorkshire.
The sample comprised three levels of ability grouping in the lower secondary school
(Years 7 to 9), with 15 schools at each level:
'Mixed Ability Schools' predominantly mixed ability classes for all subjects, with
setting in no more than two subjects in Year 9.
'Partially Set Schools' setting in no more than two subjects in Year 7, increasing
to a maximum of 4 subjects in Year 9.
'Set Schools' streaming, banding or setting in at least four subjects from
Year 7.
All schools had received satisfactory inspection reports during the three years before
the start of the project. Steps were taken to balance the three groups of schools in
terms of their size and the social mix of their intake, using free school meals as an
indicator of social disadvantage. The mixed ability schools had a slightly more
socially disadvantaged intake than the Set Schools. On average, the set schools were
slightly smaller than the other two groups. There was good overlap across groups for
both distributions.