To make most of the lectures (the backbone of the course, no?), why not prepare for them. To really make them an integral part of your course experience, why not post-pare for them also!? What do I mean...?
It is commonly accepted that it is easier to remember something when you hear it more than once. Maybe then it is placed in more than one position in your brain, with different associations triggering its location. Maybe it still sits in one location but is better interconnected with other triggers. Maybe I have no idea.
But it would certainly help greatly to not only know what is coming up in the next lecture (check the syllabus online before the meeting), but also to have spent some time in the book on the material before the show. No ?
Preparing for the Lecture
If you know the next lecture is on ( a hypothetical) Section 4.6, say, why not spend 10-15 minutes before the lecture reading through that section? You don't have to understand completely what you are reading. Some of it will make sense, some not. But at least you will be exposed to terms, concepts, boxed items, examples, BEFORE you enter the class to actually see the lecture develop the ideas. This way, the stuff you did understand on first reading will be cemented by the lecture development. You can even relax a bit on this part of the lecture.
When you get to the part of the lecture that comes from material in the book that mystified you, you can then spend some precious attention time focused. Pretty efficient, huh? We, as instructors, really do like to follow the book in many of our courses. Books are written in an organized fashion. We may embellish the material, but the core usually comes from the book.
Your notes in a lecture are an important facet of your eventual understanding. See here for some tips on taking notes.
Post-paring for the lecture
After the lecture is where the fun really starts! Here is my idea for good practice....
Grab a small block of time (another 15 minutes), in a quiet place and free from distractions, somewhere between an hour and three hours after the lecture. It won't take long. Go over your notes slowly and carefully an in your mind, relive the lecture, re-listening to the instructor and imagining the lecture hour unfold. As you f0llow your notes, you will remember things that were said that you did not write down (or finish writing down). Write them down now. You will see examples half-finished. Finish them now. You will references to the book. check them and make a mental note of them, You will make connections that you did not make before. Note them in your notes. You will see thing in your notes that STILL mystify you. Mark them (in red?) with a big question mark. Make a note to yourself to go to your TA or the instructor and ask specifically about these question marks (much of this part is also talked about in my installment of this series on Notes. Take a look there also).
All of this is called "completing the experience". It is a way to make your notes of the lectures a complete and central account of the course, as they should be. And it is a form of studying that WILL pay big dividends as the course progresses.
Try this for a few weeks. It really is a minimal effort for the benefit it offers. You will see improvement.
In bocca al lupo!