What does it mean to be refractory? (From Dickens' Great Expectations)

Resisting control or authority, stubborn, unmanageable.

This part of the Course was usually lightened by several single combats between Biddy and refractory students. When the fights were over, Biddy gave out the number of a page, and then we all read aloud what we could — or what we couldn't — in a frightful chorus; Biddy leading with a high shrill monotonous voice, and none of us having the least notion of, or reverence for, what we were reading about.

From Charles Dickens's Great Expectations.