It’s the rape and incest I think they should avoid until older.
I see your point. It has been a very long time since I read the novel (when I was in high school—not as an assignment). Of course the young black man who is accused of rape is innocent but I guess it is hinted that the man who accused him (and later tried to kill Atticus’ children) was guilty of incest...I don’t know if that is clear enough for an 8th-grader to pick up on it.