OP- your daughter could be going to the school where I work. I don't condone anyone saying a short skirt invites violence, because the statement is simply not true, but I do agree that wearing skirts so short is not acceptable in the school environment, for many reasons.
We are having a "crackdown" pardon the expression, on short skirts and makeup, and the boys with their disheveled look!
the expression is "skirts must be closer to the knees than the knickers"
It's embarrassing to watch as theses girls struggle and wiggle in these skirts, and basically show their knickers when they sit down. Sometimes it appears as if they are trying to out-do each other. Makeup as well, a girl recently came to school with fake eyelashes on. We want them to take a little pride in their appearance, to look professional.
I have to dress to a certain standard at work, I am not allowed to wear many of the clothes that I would wear everyday, it's business attire, so the teaching and support staff are subject to the same rules.
What we are trying to do is put girls on an equal footing here, stop the fashion show and get on with what matters, learning and respect for all.
I am not a prude, I love clothes, I love extreme fashions, but there is a time and a place and school is not it.