Scout leads Boo to Jem's bed, where Boo looks at Jem "as though he had never seen a boy before" (31.9).
She's got a knack for sensing Boo's mute communications. When she realizes he wants to leave, she leads him to the front porch.
Together, they walk arm-in-arm to the Radley Place. He goes inside, and Scout never sees him again.
She's bummed to realize that they'd never given him anything, when he'd given them so many things over the years.
When she turns to leave, she sees her neighborhood with fresh eyes from this spot where she's never stood before.
She shifts slightly to stand in front of the shuttered window next to the front door, and imagines how the events of the past few years would have appeared to Boo from this window—how Boo would have looked on her, and Jem, and Atticus.
Atticus always says you need to stand in a man's shoes before you can understand him. It looks like standing on the Radley porch is helping Scout understand Boo.
As she walks home through the rain, Scout thinks that she and Jem may have some more growing to do, but there's not much left for them to learn.
Except maybe algebra.
At home, Scout asks Atticus to read aloud one of Jem's books, The Gray Ghost.
Scout asks him to read it out loud because it's nice and scary, but Atticus says that she's had enough scaring tonight.
Nah, says Scout. Only books are really scary.
Atticus starts reading aloud, and Scout falls asleep.
Later Atticus puts Scout to bed, and a dozy Scout mutters that she heard every word of the story—about how they chased Stoner's Boy but they couldn't catch him because they'd never seen him, and when they found him he wasn't bad at all, but "real nice" (31.53)
Atticus tells her: "Most people are, Scout, when you finally see them" (31.55).
Wait, Atticus: you mean, like Boo???
And then Atticus heads back to Jem's room, so "he would be there when Jem waked up in the morning" (31.56).