Question

2. Why might a teacher be happy to hear her students disagree about whether a particular novel is worth reading?

Students should care about the books they're assigned.
The argument means they actually read the book.
Different perspectives help students understand the book.
Ο Ο
When students argue, teachers can take a break.

Answer 1

I think it means that they actually read the book, considering that students don’t really read books they’re assigned. :)