A new study suggests single-sex schools, despite having above-average exam results, don't help students learn. Worse, they may make students more prone to sexism. The report, published in Science, finds that previous research that found sex-segregated education improved academic performance were poorly designed and didn't account for the different socio-economic backgrounds of students at same-sex and mixed schools. Moreover, boys who spend more time in each other's company are more likely to become aggressive, the study says, while isolating girls can lead them to accept gender stereotypes. "There is no well-designed research showing that single-sex education improves students' academic performance, but there is evidence that sex segregation increases gender stereotyping and legitimises institutional sexism," said the report.