Relate ideas to other concepts presented at the same time and to ideas from other lectures. Give more focus to new materials. Write examples of new ideas in your notes. Compare notes with other classmates. You can fill in gaps and discuss key ideas.
Some teachers are difficult to understand.
Here are some tips for dealing with common problems. Fill in examples and other ideas, later. Completing reading before class and comparing notes with classmates after class really can help. Look for connections between ideas. They might not be obvious.