Just for clarification, "aantekeningen" is a note as in the notes one takes for a class (usually in a notebook), and "briefje" is a note as in something you write down on a piece of paper (such as a sticky note)?
Yes, that's it. E.g. a boodschappenbriefje is a grocery list/shopping list and natuurkunde aantekeningen are physics notes.
How does one say "I take notes"...? Is it nemen or is there a different way of saying it in Dutch?
A five syllable word for notes? Do people use a shortened version for such a common word, like just using the English version?