Well, it was probably a mistake to have the book READ OUT LOUD and ACTED OUT by the young children , which was part of this teacher's procedure. I can see why a black kid would get upset at hearing the N word over and over, spoken by his classmates.
I can't understand why the teacher did this. I remember DECADES ago, my high school doing a dramatized reading of Stephen Vincent Benet's JOHN BROWN'S BODY ( I played the voice of John Brown), which included the line "Nigger-business ain't White Folk's Business", and there was not an eye-blink in the whole school . We had exactly ONE black student, whose father was a minister in the only black church in the area---North suburban Chicago---this was a very highly rated high school just miles from where Hillary Clinton attended, and at exactly the same time.
Considering that this was done at the high school level, a talented teacher could have provided appropriate context to frame the scene properly, but if it had just been read 'cold' with no introduction then there can be problems, particularly when it's very likely a matter of the parent having zero familiarity or true understanding of the work either.
I thought I was the only person who went to different schools with famous people at the same time.