This is a great question. In chapter 9, we read of Atticus's commitment to defend Tom Robinson. Before this we think that Maycomb is a perfect little sleepy town, but we realize that it is a very racist place where justice does not exist when it comes to the color of a person's skin. Right from the beginning, Atticus says that he will lose the case. Why? He knows the reality of racism behind the appearance of Maycomb. Here is the dialogue between Atticus and Scout:
“Atticus, are we going to win it?”
“Simply because we were licked a hundred years before we started is no reason for us not to try to win,” Atticus said.
In chapter 10, we read of another difference between reality and appearance. Scout and Jem viewed Atticus as a subpar father. He was not athletic or admirable in their eyes. Little do they know that Atticus is one of the most amazing men in the town. His courage and honesty are immense. He will go on to defend Tom Robinson, but the children do not see this at all. Here is a quote that shows what Scout thinks of Atticus.
Our father didn’t do anything. He worked in an office, not in a drugstore. Atticus did not drive a dump-truck for the county, he was not the sheriff, he did not farm, work in a garage, or do anything that could possibly arouse the admiration of anyone.