I think I just used the same notebook for everything, way back when I was doing maths, and then at the end of the day pulled out the individual pages and put them in binders/folders at home for each module and organised them as I saw fit. It's impractical to carry around a ton of notepads and folders on a day to day basis so easier to keep the "central repository" of your notes at home and just take out individual things as and when you need them.