Does "take notes on (something)" mean the same as "take notes of(something)"? No. Take notes on something --> take notes on the material being presented to remember the material later (whether or not the notes are written down; the goal is to remember things for later) notes is a noun Take note of something --> be careful of something, watch out for something, observe something note is a verb Take notes on this lecture. Your exam will have questions pertaining to this lecture. Take note of the empty cupboard. Perhaps we should go shopping soon.

Thanks for your correction, Joe. Your explanation really helps.

If someone says take notes on (something), it means write down all the things I show you about (something). Saying take note of (something) is sort of a slang term, it really means "remember (something), as you will need that information later". Also, the sentence take notes of (something) doesn't make much sense, take note of (something) is better (note isn't plural in that phrase)