What does Scout say that lets her father know that she understands the truth about what happened in To Kill a Mockingbird?

In Chapter 30 of To Kill a Mockingbird, Mr. Heck Tate insists that he report that Bob Ewell fell on his own knife and died, but Atticus Finch believes that Mr. Tate is trying to merely protect Jem. He tells the sherriff that he must have Jem live honestly and face the consequences of