To this day, there are Alabamians who have negative feelings about Winston County, an area located in northern Alabama not far from Tennessee. For, it opposed secession strongly before the Civil War. Even now, in order to attract tourists, Winston County--sometimes called the Republic of Winston--plays upon its singular reputation as the "Free State of Winston" (it seceded from Alabama). As in many longer states, people from the southern part of the state have suspicions about the people from this area for a number of reasons among them the fact that some of the northern Alabamians are related to Appalachian folk (the end of the Appalachian mountain range is in northern Alabama).
Without doubt, the memory of the Civil War remains strongly in the hearts of many in Alabama and other former confederate states since battles were fought upon the ground of these states and tales are told by the old men; moreover, every single family in the South lost at least one male member of their family to this war, a fact not forgotten. So, when Miss Caroline moves hundreds of miles from the "infamous" Winston County in North Alabama to South Alabama and the closed society of Maycomb in Monroe County, where blood lines have run thin, people well wonder why she has come and become suspicious.
After Miss Caroline introduces herself in Chapter 2, Scout narrates that
...the class murmured apprehensively, should she prove to harbor her share of the peculiarities indigenous to that region.
Thus, Miss Caroline is a "foreigner," possibly a Northern sympathizer, to the children and they are suspicious. This close-mindedness gives Atticus occasion to mention his main principle of life:
You never really understand a person until you consider things from his point of view--...until you climb into his skin and walk around in it.
Scout's lesson about Miss Caroline is the first of many in Harper Lee's bildungsroman.