Books should not be banned in schools. Books are a critical part of learning and no matter what should not be restricted based on content. Although, there must be somewhere where you draw the line with an age limit. Some kids might not be mature enough to read books of explicit content. Also, a lot of books have adult content which children should not be reading. As for older grades I think they should definitely be allowed to read whichever books they want as long as the class agrees on reading one.