OP again: Back in the 80's when I was a teen, it was the trend to wear skin tight leggings or tights with an oversized top that covered your rear. I think they are trying to re-introduce the trend, but I also think that lots of people are taking it too far. I think the low rise jeans and wearing tights with a crop top is not a good trend, and not appropriate for school. I would not let DD out of the house that way.
I guess what I don't understand is why the parents are letting the kids go out of the house that way and the school has to get involved at all.
At the end of the 80s, when I was in the 6th grade, I got called into the vice-principal's office along with two other girls. I was wearing a button up top and skirt with knee length leggings underneath. The other two girls were wearing button up tops over leggings only. Faculty was concerned because they'd noticed the shirts involved in this fashion trend getting shorter over time. We were asked to turn to the side, which revealed the two girls' shirt hems came up well above the hip.
We weren't in trouble but we were asked to not wear leggings again, and the ban was extended school-wise shortly after. My mom, who had bought me that skirt/legging outfit, was pretty ticked though, considering the fact that I had a skirt on over the leggings.
Still, isn't it interesting how these fashions (and the issues they create) spiral back into style every few years?