Sounds like the teacher is very negative and unhelpful. She is probably a big part of the problem. Would she be willing to let you observe the class or could one of the guidance counselors? Is there a school psych? When I had concerns about DD, the school psych went in and observed her, then gave me a report.

In terms of behavior, she should put together some sort of positive behavior plan, like a reward or sticker chart. You will probably need the help of the guidance counselors to put something in place.