Why can't these teachers let them choose a book? Would the sky fall on their heads? I guess they don't want to risk having to read something new in order to grade the work...
Seriously. It's is so weird.
To be fair, imagine you're a teacher with 30 students, each of whom might be reading something you may never had read before. How would you know if they are doing a good job in writing a summary? I think (most) teachers love reading new books, but I can see how the logistics of obtaining the books and reading them *each week* might be difficult.
