In the beginning of Part Two, it is obvious that Jem is not suffering from a "tapeworm," as Scout suspects. Jem, now 12, is growing into puberty instead. Later in Chapter 12, Jem gets an education in African-American culture when he attends the First Purchase Church with Calpurnia. In Chapter 13, Atticus attempts to give Jem a lesson on "the facts of life." It turns out to be a speech on Aunt Alexandra's idea of "gentle breeding," and how Finches are expected to behave. Jem tells Atticus that "I know all that stuff."
In Chapter 14, Jem learns a great deal from his time spent with Mrs. Dubose. He finds out that his hot temper can only get him into trouble, and he discovers that he must pay for his mistakes. Atticus' decision to make Jem read to Mrs. Dubose teaches Jem about respect for the elderly, and he learns later about the old woman's courageous stand to rid herself of her addiction before she dies. In the end, after Mrs. Dubose dies and Atticus presents Jem with a last gift from her, Jem realizes that he has lost a friend.