
Originally Posted by
emsr2d2
If you write notes on (or in or during) a lecture, then you take notes while listening to a specific lecture - you write down what the lecturer is saying and use the notes to remind yourself later what they said. You might write "History lecture, 27 August 2011, covered American War of Independence, British industrial revolution and the role of women in the Second World War. Check relevant dates. Revise for next lecture".
If you write notes about a lecture, then you write notes about the subject of "a lecture". You might write "Lecture - a class given by a lecturer. A room full of people learning a particular subject. Sometimes called a class or a lesson. Usually refers to university, not school".