As I have started University classes again (today was my first class!), I thought it appropriate to make a 'bag contents' post about what I carry around the place. (My phone isn't actually there, just my case to represent what would be there - it's quite hard to use the phone to photograph itself ...) I'm quite practical and I often need to write things down to remember anything at all, so as you can imagine, I carry around notebooks and memos. Usually, on a day with classes, my sketchbook would be replaced with my lecture notebook.
In the end, all of my lecture books wind up being sketchbooks.