she considers to be made entirely of “exceptions.”

Martin Haberman pulls no punches in his scathing critique of the insensitive and unjust treatment received by children in poverty in the public school system. He focuses the brunt of his criticism on teachers who have been insufficiently trained for the realities of the modern school environment and whose prejudices, lack of deep content knowledge, and excessive focus on order and discipline profoundly limit their effectiveness. Haberman writes, “the principles and theories we call child and adolescent development were all developed to explain the middle-class experience,” and that everyone else in public schools, including non-white, immigrant, or non-English-speaking children, are considered somehow anomalies, thus leading to the absurd situation in which a teacher completes teacher training and is put in front of a class of students she considers to be made entirely of “exceptions.”

Does the bold sentence mean that she consider the class of students to be made entirely brilliant?

I would say she met with the situation when most of the class behaved differently to how she’d been taught they should behave–non-obediant, unwilling to work etc. Seeing this, she considered them ‘exceptions’ (I feel the author would say ‘abnormalities’).