The mind works in mysterious ways.
When you learn something for the first time, you usually pay attention, absorb some of it and probably think, "Oh, that's interesting.
" But you're likely to forget it.
The more you hear about a particular topic, the more information you absorb and consequently, the more likely you are to remember about that topic.
When it comes to difficult to material, the process is no different.
My tip then,is to read the textbook before each class.
Get a syllabus before the first class if possible or just try to find out what the professor will be covering in the first class and read those chapters.
Before each class read the handouts or chapters in the book that the professor will be covering.
Without this basic preparation, even if you sit in the front of your organic chemistry lecture and pay close attention to what the professor is saying, you will likely get lost very quickly.
Even if you can manage to follow the particulars provided in a lecture, your mind will be so busy trying to process that information that you won't actually learn and understand the deeper meaning.
If you read the material before class, whether you understand it or not, at least you will be somewhat familiar with it, and believe me, that will help.
Don't get too frustrated if you don't understand it all.
It will make sense later on.
When reading the chapter for the first time, you are simply exposing yourself to the basic concept.
You will grasp some ideas and question others.
At least you will have some foundation to build on.
When you get to class and you hear your professor lecture on the material, you'll find that you do recognize some of the information.
Therefore your mind will not be so busy trying to process the information and you can actually learn and understand it.
In this way, you can focus on the more difficult concepts being addressed and the important questions being asked and answered.
Some of the questions may be the same ones you had in mind so you will recognize them and therefore pay attention to those explanations.
This will ensure that you get a much better learning experience out of every lecture.
Best of all, if you understand what is being said, you will be able to ask better questions, which will in turn improve the quality of the information that you get out of the lecture.