Word of warning...Flatland is not for children. I don't think I want DD16 reading it.
It's satirical, to be certain, with a lot of commentary about Victorian society/gender roles, inter-class strife, and questions about identity. There is violence, but it can be skipped over. As with anything, though, I think it depends on the child. I was a child who loved the book, though I read it independently when I was older than doubtfulguest's DD (~7-8). Doubtfulguest's daughter is more emotionally mature than I was at her age.
doubtfulguest, you know your DD best. My sense of your DD is that she could handle the themes given her recent interests if it's used as a book that you read together. That way you can contextualize the material and provide a historical backdrop to the satire, even skip over any material that might not go over well.
