I agree with the others, and wonder how long this has been going on?
Has this been all year, or the last few weeks?
Has she been evaluated by her pediatrician with a referral to an occupational therapist?
Ya, if this is only happening at school something is going on. Mmarkey may have a valid point. You definitely need to visit the school several times to see what is going on.
Also, you must stop punishing her at home for what is happening at school. At this age behavioral modification must be immediate. There is no way that doing something hours after the matter is going to work (as you and her parents have found out).
I will also say as a retired elementary school principal that it was not unusual to have kids cry for the first several weeks. It never lasted longer then that. To cry for a full year would be very unusual! Which brings up another point. If she was fine for the early part of the year, and only recently has started crying - that also points to something going on at school (unless, there has been a recent family major event/tragedy).
Please post if you have more info or any more questions.
Take her out of the school immediately and switch schools. I do not feel comfortable sharing my reason on a public thread so please feel free to private message me.
By your description, it sounds as it this behavior only occurs at school. Has she stated why she behaves like this at school? There must be something that triggers this behavior especially if there is no history of this type of behavior.
Regarding discipline, it is much more effective placing a 6 year old in a form of a timeout than removing privileges primarily because she will be restricted from all activities at that time.
It seems to me that if she doesn't verbalize what is troubling her, the parents really have no choice but to seek a mental health evaluation. The school counselor should be able to assist in this matter.