You go from a general introduction, to more specific information, to a practical example. Even though they discuss different things, the paragraphs are related. So, in a sense, the three statements about level 2 statements constitute a level 3 statement. This summary indicates what the three first three paragraphs of the section on reading are about, but the summary is a little dry. Eventually, you don't have to think consciously about what you are doing.
Patterns tie everything together.
This set of sentences is at level three because each is linked to the previous one. They are a short summary of three paragraphs, which take up nearly an entire page. A good summary will always be much shorter than the original material, but it will contain enough of what was written that it would allow you to answer a question about the original text. With a good summary, you don't have to go back to the original. Everything said about taking notes from reading books also pertains to taking notes during a lecture.