1. Write down key facts.
It can take some experimenting to figure out what information really is helpful, so keep trying and don't give up. Different teachers do things differently. For example, some teachers may mention lots of dates and facts in class but only write the key ones on the board. Other teachers may not write anything down, but they may repeat a certain date or piece of information. That's a clue that it's probably important. After a while, you'll get to know a teacher's style.