Everyone's replies are so helpful! I didn't want to rush in and be the angry, overreacting parent, but I also didn't want to just let it go. All of you are confirming what I have been feeling but just wasn't sure about the best way to go about it.

I think what I will do . . .
I have a good relationship with the supervisor (I know she has a BA in education--not sure about the other staff). Because of our relationship, I feel like I can casually approach her with this. She also knows DD very well, they have a special bond. She will have a good feel for the situation. I like starting with "There may have been a misunderstanding, DD came home and told me such and such . . . perhaps she misunderstood . . ."

This will give me an opportunity to find out what has been going on. There are many nights that DD tells me these same girls tease her. I know teasing is a part of being a kid and growing up, but it sucks when its your kid There are nights where she cries and says she never wants to go to school again.