How can I take good notes from textbook (but not too many)?

For a summer assignment, we have to read a chapter out of the textbook for next year and take notes on it. There will be a 100 question multiple choice test the first day of school, and from what I've heard, it is pretty challenging. Usually I take far too many notes, in fear of encountering a very very specific question on the test/quiz, and not knowing the answer because of having ignored it when taking notes because it seemed like such a small detail. Thank you so so so much!How can I take good notes from textbook (but not too many)?
While reading your text, break each section up into key ideas/themes. With each key idea/theme look at how much detail the author goes into. If something only has two or three lines written about it, it is kind of minor; however, if an entire paragraph or two are written, it is a huge concept and will undoubtedly show up on a test! Now, take notes over this information and then once your done taking all of your notes, go through them and ask yourself questions... those questions should be written on index cards- question on one side, answer on the other. Now you have flashcards. Now it's just traditional rote learning and memorization. When the test comes up, you'll do very well.