TEACHING mixed ability groups could damage the confidence of pupils who believe they are in the bottom half of their class, a study suggests.

Researchers from the London School of Economics claim that children who achieved high grades in primary school, then perform better in secondary school not simply because they are smart but because their previous success in class had boosted their confidence.

Richard Murphy and Felix Weinhardt analysed test data of more than two million pupils in England and carried out a survey on the confidence of 15,000 young people.

They said the impact of ranking was most pronounced on boys, who were four times more affected by being top of their class than girls.

The economists believe being highly ranked during primary school is equivalent to spending a year with a highly-effective teacher.