Streaming children by ability in early primary school can widen the attainment gap between disadvantaged pupils and their better off peers.
Researchers at the Institute of Education at the University of London studied 2,544 six and seven-year-olds and found that youngsters in low streams performed significantly worse than those who were not streamed.
The pupils' backgrounds were studied and their national test results were weighed against prior attainment at age five. Comparisons were made in reading, maths and overall achievement, BBC News reports.
Approximately 17 per cent of the pupils studied were in ability streams, with eight per cent in the top stream, five per cent in the middle and four per cent in the bottom stream.
The researchers found that those in the bottom stream were more likely to have behavioural difficulties, be from poor backgrounds and to have less educated mothers.
However, relatively high-attaining pupils were found to perform better if placed in a top stream than they would have done in schools that did not practice streaming.
The debate over dividing pupils by ability was reignited earlier this month when the Guardian newspaper reported that new education secretary Nicky Morgan planned to make setting compulsory in secondary schools.
Ms Morgan denied these reports, saying there was "absolutely no truth" in the claims.
Setting differs from streaming, as the former involves dividing pupils by attainment in individual subjects, while the latter classifies them across all academic areas.
According to the Institute of Education study, one in six pupils in England is grouped in classes by ability across several subjects.
The paper concluded: "Streaming …advantages those who are already high attainers, disadvantaging those who are placed in middle or lower groups who are deprived of working with those who are more advanced."
As lower streams tended to contain a disproportionately large number of pupils from lower socio-economic backgrounds, the researchers concluded it was an ineffective means of narrowing the attainment gap and could be counterproductive.
Posted by Harriet McGowan