what happens when the teacher asks the students about the book?

Becky goes to confess, and Tom takes the blame. He is beaten unmercilously.

When Dobbins discovers his torn book and asks each student whether he or she tore the book, Tom springs to his feet as Becky is succumbing to pressure and shouts: "I done it!" Taking one of the harshest beatings ever given by the schoolmaster, Tom is inspired by his own good deed knowing that Becky will throw her thanks upon him.