If it's only to satisify your curiosity then you only need to activate the parts of the book that satisfies that curiosity right now. If more comes up later then you can come back to the book. That means you don't need to know everything now.
If it's study for exams you might want to reflect why you are studying. To satisfy your curiosity about a subject you don't need a piece of paper with a passing grade.
If you want that paper, why do you want it?
If you want to focus on the subject... what do you need to know from the text to know that subject. If you don't have any idea about that it's time to go back to your instructors... ask them how the information that you're learning can be applied to the real world that might build a decent sense of purpose for you.
Alex
