Why should boys and girls should be in the same class?

Well...

There are two options on both of my hands. On one hand boys and girls works better when the are separated, but on the other hand it is probably nice to have a friend who is a boy, or a boyfriend. Some schools think that the results will be worse, because of break ups, flirting, or kissing and being late for class. Some schools do not care too much about the results, and think that boys and girls can work well together, and that it improves the students social abilities. Also teaching methods can be different for girls and boys.

The argument is even, some schools have both sexes, some have just one of the sexes. It doesn't matter. So the answer to this question is really for social skills, friendliness, and happier pupils.