How do Scout and Jem mature during the book? What are some characteristics and qualities?
As Scout and Jem grow older, we see them come to a better understanding of other people. The novel portrays several different kinds of characters that they are puzzled by at first, or ignorant of, or even scared of, but such negative feelings gradually decrease as they mature and they come to realise why these characters act as they do. Perhaps the most significant, and certainly the most touching, example of this is their reclusive neighbour Arthur Radley whom they initially nickname 'Boo' as they conjure up all sorts of childish fancies about him, that he is a fearsome monster. But by the end of the book Scout realises Arthur's sterling good qualities and the fact that, far from being a threat to them, Arthur has actually been protecting them. The reverse of this lesson is that people who might appear normal and civilised might actually be less than good; Scout in particular comes to realise the unpleasant racism and sheer hypocrisy of the supposedly genteel, refined ladies in the neighbourhood.
Growing up also means being able to have better self-control. Scout at first tends to lose her temper and lash out physically at people, but in the course of the book we see her being able to hold herself in more, even when the neighbourhood taunts her and Jem about their father defending Tom Robinson. And when news comes of Robinson's death during a dinner party, she is able to compose herself enough to help Aunt Alexandra take in the dinner tray.