I tend to take notes from the textbook readings, jotting down important points. Everyone's method of studying is different. I think it is important to know what format the exams are. I remember taking a math class and I was prepared for the applied problems, but I bombed the first exam because it was 50% vocabularies (not what I expected). I did not see that coming and the teacher was not very clear in her review. I think it is best you speak with your teacher about your concerns and ways to raise your grades. Some teachers are nice and they will offer extra credits to boost the grades. Teachers are there to help you. Don't be afraid to ask for help. They won't bite