Well, if the reviews indicate things this teacher actually did in class, then her firing seems justified.

From Amy Biolchini of MLive:

Ann Arbor teacher files lawsuit over removal from classroom based on bad online reviews

An Ann Arbor high school teacher accused of arranging her class seating chart by race, calling students names and making disparaging remarks to her pupils had a history of reprimands for at least five years before she was removed from the classroom.

But it was after a parent relayed negative online reviews of the teacher — including the allegation that she verbally abused students — that the district placed her on paid administrative leave.

Ann Arbor Public Schools administrators put Dianne Down, a tenured math teacher with 14 years of employment in the district and a 32-year career as an educator, on leave in December.

The district only cited a need to investigate allegations that Down had verbally abused her students in the letter placing her on leave, according to documents obtained by The Ann Arbor News through a Freedom of Information Act request.