What is it?
Students with similar levels of current achievement are grouped together either for specific lessons on a regular basis (setting or regrouping), or as a whole class (streaming or tracking). The assumption is that it will be possible to teach more effectively or more efficiently with a narrower range of achievement in a class.
How effective is it?
Overall, regrouping or streaming appears to benefit higher attaining students and be detrimental to the learning of mid-range and lower attaining learners. On average, it does not appear to be an effective strategy for raising the achievement of disadvantaged students, who are more likely to be assigned to lower groups.
Low attaining learners who are set or streamed fall behind by 1 or 2 months per year, on average, when compared with the progress of similar students in classes with mixed ability groups. It appears likely that routine regrouping or streaming arrangements undermine low attainers’ confidence and discourage the belief that achievement can be improved through effort. Research also suggests that ability grouping can have a longer term negative effect on the attitudes and engagement of low attaining students.
In contrast, studies show that higher attaining learners make between 1 and 2 additional months' progress when set or streamed compared to when taught in mixed ability groups. This is unsurprising: studies of targeted interventions for students identified as "gifted and talented" show that they benefit from a range of different kinds of grouping, including pull-out classes, accelerated classes and promotion (where high attaining students move up a year). However, research into gifted and talented schemes rarely records the impact of the schemes on the students not identified as gifted and talented, who are more likely to be from disadvantaged backgrounds. It is possible that, as with regrouping and streaming, those not identified as gifted and talented experience a negative impact.
Though the average impact of regrouping or streaming on low attaining students is negative, evidence suggests that certain types of grouping are more effective than others. Some studies have shown that reducing the size of the lowest attaining groups and assigning high-performing teachers to these groups can be effective, as can providing additional targeted catch up support (see small group tuition).
In Australia, there is a strong culture of streaming in schools, even though it has not been adequately shown to considerably improve student achievement, and some research suggests it can actually be detrimental. In Australian schools, the most common practice is setting. This is where streaming occurs for only a few classes, commonly literature and numeracy classes, without explicit targeting and rearranging. An Australian study that examined the effect of streaming for primary students in New South Wales found a zero to negative effect on student outcomes.
A 2012 OECD review concluded that setting or streaming students is not associated with higher outcomes at a system level, and that students from low-income families are likely to be negatively affected.
How secure is the evidence?
The evidence on regrouping and streaming is fairly consistent and has accumulated over at least 30 years of research. The majority of the evidence comes from the USA, and there are few rigorous UK studies. Although there is some variation depending on methods and research design, conclusions on the impact of ability grouping are relatively consistent.
What are the costs?
Setting and streaming are organisational strategies that have few associated financial costs. Additional resources may be needed if regrouping or streaming resulted in greater numbers of classes. Overall the costs are estimated as very low.
Setting and streaming are organisational strategies with few, if any, associated financial costs. Additional resources may be needed to support different groups. Overall the costs are estimated as very low.
What should I consider?
For low attaining students, flexible within-class grouping is preferable to tracking or streaming.
It is important to recognise that a measure of current achievement, such as a test, is not the same as a measure of potential.
How will you ensure that your regrouping or steaming approach enables more effective teaching for all students, including lower attaining students?
How will you monitor the impact of ability grouping on student engagement and attitudes to learning?