In many Catholic schools, where families of students pay an amount of money every month, the boys and girls are taught separately. However, there are arguments both for and against it.
One of the advantages is that the student's result improve. Another argument is that in this way the kids have no sexual attraction to girls and vice versa, in this way children focus in their studies. Although the possibility exists that there are people who feel same-sex attraction, but it would be a minority.
On the other hand, being taught separately is an inconvenientce. Children doesn't learn how to live with people from the opposite sex and in the future, they can have problems when relating to women/men.
On balance, there are a lot of opinions, good ones and bad ones and we have to understand and respect all of them.