in all seriousness, there is nothing to teach, it is something which one will know naturally. with muslims you will have to teach your child about marriage staying away from luedness and adultery and therefore through this type of education they will know what not to do and therefore they will know their rights and responsibilities.
as for todays society it is silly to think that one needs to teach 'sex education' but today we have this lame subject because the system has it wrong, they do not encourage marriage but encourage adultery and sleeping around, i mean the latest news, is that, teenage girls can order the morning after pill via text message, if this is not encouraging sleeping around then i do not know what is.
If this society is encouraging this lued form of behaviour then why don't they show them the real side of things. like in islam it is taught that one gets married has rights over his wife and his wife has rights over him, both parties have responsibilities etc.