Ms. trinh is about to start a unit on sharks. some of her students have a strong interest in sharks and know a lot about them. others know very little about sharks. when ms. trinh gives a reading assignment about sharks, she should expect that

Ms. Trinh should expect that students who has interest and knows more about shark would find it interesting to read the book and will motivate them to listen to her. And she should expect that those who does not know more about sharks would likely find it less interesting and would be hard to motivate them in terms of the topic that she's going to discuss.

An informal structure in a bureaucracy would be something like so-called "office politics". where there's a formal structure set up for the organization, but then an informal subculture as well that has a way of organizing the bureaucracy further. this can be positive because it sets up an added degree of organization, albeit informal, within the bureaucracy.