If a civil suit has been filed against the school (and the teacher is not a party), then the attorney for the school should ensure that the plaintiff adheres to the proper procedures concerning discovery. It sounds as if this was not a properly scheduled assessment. The school's lawyer should be advising the teacher, if nothing else, to prevent prejudicial admissions by the teacher when she is being "observed." If the teacher is going to be scapegoated, then she needs her own attorney in the event she becomes a party to the suit. I have served for many years as an expert in civil suits involving schools, and I have never been granted this type of access to a teacher. Contact me if you want to discuss this further.