If you have physically challenged students, you might want to look at the Digilock Locker Locks.  They offer 3 models for the various types of applications you may have.  The first model is the T30, which is designed for lockers with handles and a vertical locking bar.  The locking bar is the piece that moves up and down inside the locker door.  The second model is the T52, which is designed for single point lockers.  A single point locker is one were the door latches at a single point.  The third is the T70, which is designed to be used on all metal locker applications.  All of the Digilocks are ADA Compliant, feature one touch access, easy installation, a high security latchbolt (1/2″ deadbolt), audio or visual indicators, non-handed, nickel finish, and operate on 4-AA or 4-AAA batteries  (included) with a life of 3-5 years.

the above image is a brochure on the Digilock Locker Locks