Notebook.
(You sure have a lot of threads about studying habits…)
Notebook. I’m currently a fan of multi-subject notebooks for all of my classes. All of my notes in one place; very compact and neat. I sort important documents in the folder pockets of the dividers.
Composition notebook. I have one, use it for all my classes. I hate spiral notebooks because the spirals get caught on everything and it’s just a mess.
I use a multi-subject notebook. It’s almost impossible for me to lose it.