One of my DGDs, who turns 12 today, is very interested in the Holocaust and has read a lot about it, including several novels. I have bought her The Diary of Anne Frank as one of her birthday presents. Sympathy for the victims has prompted her to read novels about children who are modern day refugees. I think that her sister, who turned 10 yesterday, would be able to cope with those books if she was interested. However, I am not sure that they wouldn't find a film more upsetting. Possibly.
In general, I don't object to schools teaching about traumatic subjects, if it's done with sensitivity. However, when my elder DD was at secondary school they had a lesson where the teacher talked about and showed them photos of serial killers. I have no idea why. My DD became particularly frightened of Dennis Neilson (sorry, don't know how to spell it.) She even dreamed that he was trying to get through her window to get her. I had to talk to her and explain that he was in prison and wouldn't be coming out, and that he wasn't interested in girls anyway. We managed to make it into a joke about "your friend Dennis", to take away the fear. That was 30 years ago. I have never understood why they thought it was a suitable subject for kids. I can see that it's important to make them aware of the danger of being attacked or abducted, but this was more like a social history lesson. It certainly scared the hell out of my DD.