In the past, most of schools were only for boys or only for girls. Now, it has changed and most of the schools are mix. However, there are arguments both for and against it.
One of the main advantages of mix schools is that they help getting smaller the differences between boys and girls. It helps to reduce the machismo that still is in our society. Another argument in favour of mix schools is that it helps in the interrelations between the opposite sexes and helps to have friends which aren’t the same sex you are. It is obvious that if you are all the day in contact you start friend relationships easier than if you aren’t.
On the other hand, in mix schools boys and girls can be distracted when they are teenagers by the attractions they have to the opposite sex and slow their learning. Moreover, girls and boys often have a different way of learning for example in the sports class girls are often more flexible than boys and boys are stronger and faster.
On balance, I would say that although boys and girls can get distract when they are though together, boys and girls shouldn’t be taught separately because it helps to reduce the machismo.