How does point of view help the reader understand Scout in Chapter 3 of Harper Lee's To Kill a Mockingbird?

The point of view is actually the exact same all throughout Harper Lee's To Kill a Mockingbird. All throughout, Scout narrates the story using first-person point of view, which is even the case in Chapter 3. Although, it can be said that we learn some new things about Scout through the first-person narration in Chapter 3. In particular, we learn that Scout has a very quick, irate temper and even some prejudices she must learn to overcome.

Scout's quick temper is especially seen at the start of the chapter when she relays being stopped by Jem from "rubbing [Walter Cunningham's] nose in the dirt" because she blames Walter for her having gotten into trouble on her first day of school. The reality is that Walter rejected Miss Caroline's quarter because he has been taught to have a sense of pride despite poverty, and it was not Walter's sense of pride that got Scout into trouble; instead, Scout's attempt to explain Walter's poverty and his sense of pride failed because she came across as a know-it-all, even a little bit arrogant. Therefore, we learn through Scout's first-person narration at the start of Chapter 3 that Scout is quick to blame and attack others because she has a very quick and irate temper.

After Jem invites Walter home for lunch, during lunch, Scout describes through her first-person narration another mistake she makes, and this mistake shows us that, not only does she have a quick temper, she has prejudices she needs to overcome. When Walter asks for the molasses syrup and pours it all over his plate, Scout shames him by asking him "what the sam hill he was doing." Walter's heartbreaking shame is recognized in Scout's following narration:

The silver saucer clattered when he replaced the pitcher, and he quickly put his hands in his lap. Then he ducked his head. (Ch. 3)

When Scout is reprimanded by Calpurnia in the kitchen, who argues that Walter is Scout's company and needs to be treated with respect, Scout reveals her prejudice against Walter and people of his social class when she retorts with the following remark: "He ain't company, Cal, he's just a Cunningham--." However, as the novel progresses and Scout learns from Atticus, Scout sheds her prejudices and becomes deeply offended by others' prejudices, such as her aunt's prejudices.

Hence, all in all, Scout's first-person point-of-view narration in Chapter 3 reveals to us that she has a quick, irate temper and prejudices, both of which she overcomes as the novel progresses.