It's not clear how robust these findings are to cultural variations (or age group variations), but here's the main result from a study on school children in Israel:
Boys benefit from being in a classroom with girls, but girls do not benefit from being in a classroom with boys.
Here's an extended excerpt:
Their answer chimes perfectly with the conventional wisdom: Boys benefit from being in a classroom with girls, but girls do not benefit from being in a classroom with boys. What is interesting about Lavy and Schlosser's work is that it uses survey data provided by the children to work out what is causing the effects. The survey questions ask, for example, about violence in school, respect for teachers, classroom distractions, and relations among students.
Boys pollute the educational system, it seems, for a number of unmysterious reasons: They wear down teachers, disrupt classes, and ruin the atmosphere for everyone. And more boys are worse than fewer boys, not because they egg each other on but simply because more of them can cause more trouble in total.
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Thanks to Sharath Rao for the e-mail alert.