Varies, I see plenty of backpacks though. Personally I just carry my laptop (and only when I absolutely need it) in a little slip cover bag provided by the school, along with my coffee cup/tumbler in hand. Most people also use lockers, again something I've found not necessary (but people seem to really depend on them *shrug*). One classmate I used to sit next to would bring a backpack and another bag, often filled with snacks/food. 🙄 I should've taken advantage of her snacks, but I always felt bad asking.
I leave my loupes in one of my personal drawers at my lab bench, something I think most people don't do (they carry around that lunch pail case, or leave it in their locker). Lab coat just hangs in the car when needed. It's all just personal preference.