Gender roles in a nutshell: the Beauxbatons and Durmstrang entrances in The Goblet of Fire.
also, to my knowledge neither of those schools were sex-segregated in the books
That bothered me more than the Dumbledore yelling, actually.
Nicolas Flamel was an alum of Beauxbatons.
The first headteacher of Durmstrang was a witch.
Bam.
In the books, it even says that there were boys and girls from each school. Thanks Hollywood for making Durmstrang buff and all athletic men and Beauxbatons all feminine and dainty.