[QuantumIguana]

In music class, students don't all play the same instruments, in choir they don't all sing the same parts. In art class, students don't all paint the same paintings. When students do research papers they don't all do their papers on the same subject. Thus it is not true that students desires have no bearing in any other class. It's common for students to have at least some degree of choice in the classroom.

In math class, there isn't some other math that would do as well as what is assigned. This isn't true in literature. Students could learn just as well from a number of books, and they will be more likely to learn from a book that interests them than from a book that doesn't.