One way that Harper Lee explores traditional gender roles is in how people expect Scout to behave.
Scout is a tomboy. She prefers overalls to a dress. She likes to play outside. She gets in fist-fights with boys. She is not lady-like. Even though her name, Jean Louise, is feminine, most people call her the more boyish “Scout” instead.
For most of the book, calling Scout a girl is how her brother Jem insults her.
"See there?" Jem was scowling triumphantly. "Nothin' to it. I swear, Scout, sometimes you act so much like a girl it's mortifyin'." (ch 4)
Yet Scout is a girl. Jem seems to forgive her for that most of the time, until she says or does something that he doesn’t like. Then he brings up the girl stereotype.
Jem told me I was being a girl, that girls always imagined things, that's why other people hated them so, and if I started behaving like one I could just go off and find some to play with. (ch 4)
Jem changes his attitude as he gets older, and he starts to feel like Scout should act a certain way, telling her "It's time you started bein' a girl and acting right!" (ch 4).
In fact, everyone tells Scout how she should act. Her aunt thinks she should wear a dress and sit in on parties.
I could not possibly hope to be a lady if I wore breeches; when I said I could do nothing in a dress, she said I wasn't supposed to be doing things that required pants. (ch 9)
Aunt Alexandra has the stereotypical view of a girl playing with dolls and tea sets.
There are also examples of society’s attitudes toward women and girls when at the rape trial they want to clear the court-room because the topic is not appropriate for ladies. Atticus also expresses a sexist view of women when explaining to Scout why women can’t serve on juries.
I guess it's to protect our frail ladies from sordid cases like Tom's. Besides," Atticus grinned, "I doubt if we'd ever get a complete case tried- the ladies'd be interrupting to ask questions." (ch 23)
As forward-thinking as Atticus is on matters of race, he is not so on matters of gender.
Yet by presenting us with Scout, Lee gives us hope for change. If all girls acted like Scout, perhaps more women would someday be on juries. Women can be smart and independent.