This is a great question, and one that I struggle with as a junior high and high school teacher. I need answers just as much as elementary teachers do. I want to accurately and comprehensively teach about the way things are without making anyone needlessly uncomfortable, and I haven’t found a way of doing this that consistently feels right to me. It’s not just racial issues, either; any time I teach about something that touches on a student’s identity—like socioeconomic status, religious/denominational background, or health challenges—I worry about being insensitive, especially when I suspect that the student’s sense of his identity is not entirely positive.
One thing that I’ve found helpful when teaching about racial discrimination and similar topics is to root the discussion in human nature rather than the particularities of the situation in question. (Not that the particularities can be ignored. They’re important, but they’re fruit, not the root.) People mistreat those who are different; we all know this is true, and have experienced it from both ends. Making the story an expression of our common fallen humanity helps to avoid harmful feelings of guilt, victimhood, or alienation among those who have reasons to identify with the story’s characters.