same gender or different

I think co-ed schools are the best because that way students learn to mix with a variety of people rather than just members of their own gender. Teenagers will always want to know about their opposite gender and if they don't have that in schools then they will surely go looking elsewhere for someone to flirt with and test themselves. In a setting other than school, that can soon lead to trouble. Also I believe that boys and girls are competitive and so by being educated together, they will strive to improve and do their best. :)