At school, I only have one notebook. I pay attention to the teacher and whenever I don’t understand something immediately, I redo the demonstration on paper. There were a few teachers that didn’t use textbooks or slides so I had to rely on friends and photos to review things later. But the real advantage is that I usually understand the subject deeper. I did well on explanation questions, not so on memorization question. But I could always guess the answer.
It took at least two rounds condensing the information down onto such a small note. Often more.
After that I didn't need them for the test.
I only later understood that this was a great way to learn as a system.
Extract - Condense - Extract - Condense
In school it never occurred to me that I was learning. I thought I was trying to cheat and only got lucky to know stuff.