I think it's very reasonable to pick and choose what is appropriate for an 8 year old. There are many movies for example I wouldn't show an 8 year old because they are too violent. I do think being exposed to things that bother her will eventually help the anxiety. But no need to be extreme about it. Having her learn through history about bad things is probably a good way to expose her.
I agree that movies (and tv) are another matter and that age appropriate choices are good.
I am fairly sensitive to violence in movies and my kids are too. I don't think that's a bad thing. We do try to keep them aware of what peers are watching when possible, for social reasons. But I think movies operate at a far more visceral level than reading does, and needs to be handled differently. IMO.
