Books are resources and are not graded. As an alternative, you might want to check out the Content Pages (mod_icontent) activity. It can be set up as a graded activity and has a table of contents for navigation, just like the TOC for books.
It has a lot of capability that makes its pages resemble and behave like slides in presentations. The grading is from points earned when answering questions the teacher includes on various pages. Questions can come from your regular question bank although not all types of questions are currently supported.