In To Kill a Mockingbird, how do people instill conscience in Macomb's children?

In general, Maycomb's children in Harper Lee's To Kill a Mockingbird are instilled with conscience by being taught right and wrong by their elders and by life's events. However, Scout, Jem, and Dill are really the only three children the reader observes being taught right and wrong, and numerous examples can be found all throughout the book.

One example found early on in the story is when Scout is reprimanded by both Atticus and Calpurnia for her treatment of Walter Cunningham Jr. the day Jem invites him home for lunch in Chapter 3. Jem invites Walter home for lunch when he finds his sister rubbing Walter's nose in the dirt and makes her stop. At the dining room table, Walter enters into a very adult-like conversation with Atticus about farming when Walter asks for the molasses syrup and pours it all over his plate. Scout interrupts him by asking him "what the sam hill he was doing," making him feel ashamed, as seen when he lets the pitcher fall back with a clatter, puts his "hands in his lap" and "duck[s] his head." Atticus shakes his head at Scout, and Calpurnia requests her to come into the kitchen, where she gives Scout the following scolding:

Don't matter who they are, anybody sets foot in this house's yo' comp'ny, and don't you let me catch you remarkin' on their ways like you was so high and mighty! Yo' folks might be better'n the Cunninghams but it don't count for nothin' the way you're disgracin' 'em. (Ch. 3)

Towards the end of the novel, Scout has learned her lesson, as evidenced by the fact she wants to invite Walter home for lunch again and by the fact she tells her brother she sees all people as being exactly the same: "I think there's just one kind of folks. Folks" (Ch. 23).

We also see development of conscience in Jem in many different ways. One example can be seen with respect to his treatment of Arthur (Boo) Radley. Soon enough, Jem realizes that Arthur had been leaving Jem and Scout gifts to find in the knothole of the oak tree on the Radleys' lot. He also realizes Arthur had mended Jem's pants out of kindness. Both of these realizations help Jem to see that Arthur is actually a kind and caring person who has been misjudged by society. Jem decides to leave Arthur a thank-you note in the tree but is prevented from doing so when Nathan Radley cements up the hole. When Jem realizes he has no way of repaying Arthur's kindness, he is overcome with guilt, which is reflected in his tears. As Scout notes, the evening they find the knothole cemented up, Jem stand outside for a long time. When he finally comes in, she "saw he had been crying," a sure sign of his remorseful feelings (Ch. 7).