Is there anyplace you could lock up the bike inside? In my school in downtown (high school) there is a designated hallway with hooks to hang up bikes, maybe there is something similar? If not, even if you could lock it to an indoor railing in view of a receptionist area or security camera would be safer than on the street.

I use a kryptonite mini-u to lock up my frame when I'm just inside for a few minutes and hope my lack of quick releases will deter casual thieves. I also have a kryptonite chain and padlock for longer term stays, and I haven't had anything stolen yet! (knock on wood)

no, more like garage.

Sheldon style* lockup in Lambeth, London:

(*OK, the lock is around the seat tube as well).

Personal pet peeve here-a bike chain is a silly way to lock a seat on. Simple to defeat, and heavy. Yes, it is better than nothing, but just filling the allen heads on the seat bolts works better, and it harder to defeat.

My unthreaded headset needs it's allen-access caulked over... and more railing's, you aren't supposed to have your bike on, they're for handicapped peoples and emergencies. I've been threatened a few times for locking mine to a railing that leads to a locked gate. Go figure, be thankful your school has it so nice for you! That's a long time that your bike'd be spending outside!

I use two mini u-locks and a chain at times