My view is that children should be brought up with each other, learning from each other, and learning to respect each other as guided by their religion even when they are biologically of different genders. The being togetherness is very good for a cohesive and learned society. I am against single sex schools because boys and girls should not be isolated from one another as they grow up. It does not give them all round development. Indeed, it may be Muslims and Christians (and especially the Catholics) who introduced the idea that it was desirable for society to have separate education for boys and girls to keep them apart in case it arouses sexual desires and distracts them for the envisaged roles that men and women are meant to have according to God presumably.
The religion of Sikhism seems exceptional in that it is supposed to promote gender equality intensely as a fundamental characteristic of Sikh society. It appears to go to great lengths to enable this. To examine how far this is true in the way the religion is practiced now, I set up the following thread in Religious Forums: http://www.religiousforums.com/forum/sikhism-dir/149271-does-sikh-religion-prescribe-separate-education.html. My question was does the Sikh religion (by which I mean the doctrines in holy Guru Granth Sahib or the words of any of the individual Gurus during their life times) prescribe or advocate the separate education of boys and girls for the ages 5 years to 16? Are girls and boys allowed to sit together in the same class room to be taught together? Do they have different curriculum, that is different things being taught to boys and girls?
It appears that there is nothing in the fundamentals of Sikhism that says that boys and girls should be treated differently in their education in terms of what they are taught or that they should be taught in different schools. They can sit in the same classroom and do not even have to sit on different sides of the room to keep boys and girls segregated. They can therefore learn from each other, about each other and from the teacher through the process of common sharing of facts, ideas, principles of dharma and the practice of the worship of God. God as Paramatma is known to Sikhs as being both masculine and feminine at the same time. The names of boys and girls are gender-neutral in that both sexes can be given the same name. It is not the case that only boys can be preachers and girls have to be wives, mothers and look after the home running. Girls and women can be engaged in singing hymns in all spiritual proceedings in the gurudwara/temple and outside and in playing the harmonium and tabla. Thus, it appears that both sexes are allowed to lead religious congregations, and undertake Akhand Path, Kirtan, Granthis and perhaps also missionary work (: http://en.wikipedia.org/wiki/Women_in_Sikhism). Gurudwaras that do not encourage girls to become preachers and undertake these activities may be going against what Guru Nanak and other Sikh gurus taught.
If the impression I have of Sikhism in these fundamentals is borne out from scriptural studies I will have a great deal of respect for the religion.