How does the scene in chapter 3 anticipate the plot development during the trial and conviction of Tom Robinson?

In chapter 3, Scout has a conflict with Walter Cunningham, whom she feels superior to because of her higher social status. Walter Cunningham is from one of the poorest families in town, and Scout is aware of that and considers herself better than him because of it. This foreshadows the lesson she learns during the trial—that people should be judged by their behavior, not by their social status or race or anything else. In this chapter, the Cunninghams are contrasted to the Ewells. The Cunninghams have honor and the Ewells do not, but they are both looked down on because of their poverty.
Atticus explains to Scout that the Ewells are dishonest people who live like animals and have no self-respect. However, he tells her that she should not judge the children for their parents’ behavior and that it is important to understand a person’s circumstances in order to understand how their behavior and attitudes develop. Atticus tells Scout, “You never really understand a person until you consider things from his point of view.” This foreshadows the understanding Scout gains during the trial of Tom Robinson, when she sees how both Tom Robinson and Mayella Ewell have been victimized by their circumstances.