Here's a formula for finding the important ideas in a chapter.
1.) GET THE BIG PICTURE FIRST
2. READ EACH SECTION WITH A QUESTION IN MIND
3. MARK INFORMATION THAT ANSWERS YOUR QUESTION
4. CONFIRM YOUR ANSWER.
Does the information you marked answer the question you made?
Repeat this questioning, reading, and confirming the process until you are ready to stop.
Then, do a brief review of what you read to pull the ideas back into a whole. You can review