Giving lectures, on the other hand, is the most efficient way to learn.
this is truer than most people realize. i had a teacher who divided the syllabus into parts at the start of the semester, and gave each student one part to teach. everyone knew their parts well in time and had time to prepare. the portion i had to take up, i didn't even need to study for the final, just the other topics. i wonder how well my score could have been if i would have taught the whole syllabus.
Yet, no matter how you take your notes, attending lectures is the least efficient way to learn.
i don't know about this. many people don't attend lectures and get copies of notes from multiple people. then decipher those notes, and make their own notes. i tried it a couple of times (classes are boring!) and i feel this is the least efficient way to learn. people take notes for themselves. the notes are full of individual quirks, mnemonics, povs to look at a concept, etc. it's very tough to grasp the crux, and form your own understanding. in comparison, teachers usually present the topic as is, without much of an individual spin.