"Hi, Harry! Hi, Ron! We're just practising some Charms. Why don't we practise casting Alohomora? We haven't used it for a while."
—Hermione Granger opens the practise session.[src]

Unlocking O.W.L. Revision was the name of a practise session led by Hermione Granger for several Hogwarts students, including her friends Harry Potter and Ronald Weasley, sometime during the 1994-1995 school year. It was held in Classroom 2E, presumably with the permission of Filius Flitwick. It was focused on practising the Unlocking Charm, Alohomora.

After a simple practise test of the spell on a locked chest, Hermione challenged the class to find Flitwick's baton, which she had hidden behind one of several locked doors in the classroom. Though many students struggled to complete this session, Harry and Ron completed it perfectly.