Racial prejudice can be found within the trial of Tom Robinson vs. Mayella Ewell. The jury finds Tom guilty of raping Mayella, even though Atticus makes it obvious that this was not what actually happened. Social prejudices can be found through the actions of Aunt Alexandra and the way that she refuses to see the Cunningham's as equals to the Finches. She even tells Scout to not talk to Walter because he is of a lower social status. Finally, gender prejudices can be found through the treatments of Scout vs. Jem or Dill. Many women within Maycomb, Aunt Alexandra, Stephanie Crawford, Mrs. Dubose, believe that Scout should act feminine. They frown upon the fact that Scout enjoys getting dirty and hates to wear skirts. I hope this helps!
Look at the way that the characters of the novel interact and you will perceive the attitudes that are prevalent about these characters as each of the characters in "To Kill a Mockingbird" provides a view of human nature. For example, Boo Radley who does not leave his home and has a bizarre reputation and Mr. Dolphus Raymond who lives with a black woman on the "wrong side" of town are both social outcasts. One day outside the courthouse Mr. Raymond explains that he drinks his Coca-Cola in a brown paper bag so that people will think he drinks liquor; this bad habit will, then, provide them a safe explanation for his lifestyle. Yet, he is still ostracized and is another social outcast.
Of course, the most glaring prejudice is the racial one. Tom Robinson steps over boundaries when he aids the Ewell girl and is convicted of a crime because of his color, not his actions. Finally, a social prejudice is evident in the interaction of the townspeople with Atticus Finch. One day a group of men come to Atticus and question his motives for defending Tom, demonstrating racial prejudice against Tom and social prejudice against Atticus. This bias against Atticus reoccurs in the children's insults of her father to Scout.