I am a high school student, and my deskmate has been in the top three in math. I read his notebook (the usual mistakes and examples written by the teacher on the blackboard are recorded on it) and then classified it. For example, I take math elective 2-2, the first chapter of derivatives and then copy important concepts, and then many questions are written in black pen, and then I write my own answers in black pen, and my own ideas and important ideas ordered by the teacher are written in blue pen (more eye-catching, he said).