mdd: sorry I was unclear.
Basically I personally abide by the halachos of tznius, but only because of the community I associate myself with. I would really like to understand where the halachos come from. I’m sure that if girls (and women) were taught halachos of tznius (and not just told to cover) they would dress accordingly. In all my bais yakov years not a single teacher or Rabbi showed us a textual source of tznius guidelines. It was taught more as a sensitivity/hashkafa subject.
So can anyone tell me where it says I have to cover my whole knee at all times?