Three theories of notetaking
Theory #1. Record everything you can.
This works okay if you are fast writer.

Theory #2. Record whatever is written down on the board.
This works okay if the teacher writes down the main points on the board.

Theory #3. Record what you think is best.
This works well if you know what you're doing. It helps if you ask the teacher what will be covered next time. Then spend 3 minutes previewing before class.