What's a justifiable reason for assigning a book? What should be your rationale?

I'd think the book, first and formost, must promote a healthy and constructive perspective on life. That is it promotes a positive attitude. If a book deals with constroversial topics, but presents them in a way that glorifies the controversial or promotes an unhealthy lifestyle then that should not be assigned in class. But if a book deals with issues in a way that makes them less than attractive, or if the issues contribute to the conflicts within the book, then it might be worth assigning to simply be able to talk about the issues in class. I think any book that deals with a controversial issue and promotes it as positive should be used with caution. And beyond any personal feelings about a book a teacher may have, it is the teacher's responsiblility to have active communication with the parents to ensure no one has any glaring issues with the text assigned, and if there are concerned parents to speak with them about your rationale for choosing the text. Parents have the responsibility in reering children, and teachers/schools are given permission to partake in the reering of children, but we do this with the parents in mind first. We are partnering with the home as teachers, or at least that's the perspective I take on the issue.