There’s what you assign, and then there’s what they read. In most classes, those two are not the same. Textbook costs often prevent students from buying the book in the first place. When that happens, what starts as an economic issue quickly becomes an academic issue (and then can become a financial aid issue). A great book that goes unbought and unread isn’t as good as a pretty good book that a student actually reads. Classes go better when students do the reading.