My daughter is about their age. Here some books that she really liked, that I think do a good job talking about the virtues you are looking into.
Most of these come from my Daughter's "Project Lit" club at school, which has just been amazing at finding great books she enjoys reading which also teach her about the lives of other people. I would highly recommend taking a look at their book lists and seeing what you think would interest the kids:
https://www.booksource.com/Departments/Booksource/Special-and-Regional/Project-LIT-Book-Club.aspx
You mean this one?: https://www.amazon.com/Wonder-R-J-Palacio/dp/0375869026
That wasn't it. (I read Wonder long ago) The book I'm looking for was one of those flat, hardcover children's books with illustrations on every page (2D ones, if I remember correctly). Thanks anyway!