How can we tell that Scout is maturing in the tea party scene of Kill a To Mockingbird?

The scene shows that Scout is maturing because she feels empathy for Aunt Alexandra and understands how the ladies are being hypocritical.

Scout’s father spent most of her childhood trying to teach her the subtle art of empathy.  Empathy is part of maturity, however, and it was something that took Scout time to learn.  We see that Scout has matured by her behavior during Aunt Alexandra’s missionary circle meeting.  Scout says the meeting is “part of her campaign to teach me to be a lady” (Ch. 24).  Scout is supposed to wear a nice dress, help serve, and behave herself.

The meeting is not without incident.  Some of the ladies tease Scout, asking her questions adults seem to always ask kids, like what they want to be when they grow up.  They laugh at her response and tease her for going to the courthouse.  Miss Maudie holds her hand in quiet support.

The first challenge in the meeting comes when the ladies begin describing squalor in Africa, the cause of the day, and the conversation switches to Helen Robinson.  This is dangerous territory because Atticus is defending Tom Robinson.  Miss Maudie finally can’t take the hypocrisy and makes a comment.  Scout notices Alexandra’s reaction.

Aunt Alexandra got up from the table and swiftly passed more refreshments, neatly engaging Mrs. Merriweather and Mrs. Gates in brisk conversation. … Aunt Alexandra stepped back.  She gave Miss Maudie a look of pure gratitude, and I wondered at the world of women. (Ch. 24)

Even though she is not really old enough to understand what is going on, Scout is mildly aware of the hypocrisy of claiming to care about starving people in African while ignoring and patronizing the blacks at home.  She also understands that Miss Maudie stuck up for Aunt Alexandra and Aunt Alexandra was grateful.

It is at this same party that Atticus tells them what happened to Tom Robinson.  He was shot while trying to escape.

“This is the last straw, Atticus,” Aunt Alexandra said.

“Depends on how you look at it,” he said. “What was one Negro, more or less, among two hundred of ‘em? He wasn’t Tom to them, he was an escaping prisoner.” (Ch. 24)

Again, Miss Maudie supports Alexandra.  She is deeply affected by Robinson’s death, thinking of how it affects her brother.  Scout watches Miss Maudie shore up Alexandra, and they all go back in and face the other ladies with their heads held high, like nothing happened.  They are three ladies putting up a brave front.