Children learn about the world around them through what they see adults, siblings and neighbors do and say. Children also have a tendency to take things quite literally, which can cause misunderstandings when idioms or figures of speech are used. And for the most part, children are honest about what they experience, which can also cause misunderstandings between what adults find is or isn't proper in different circumstances. With all the different social rules to remember, especially in the South, children can find themselves in situations where their childish instincts burst forth without any filter or restraint because they don't know any better.
One of the first examples of childish instincts erupting is when Scout reacts loudly to Walter drowning his dinner in maple syrup. Scout is shocked and doesn't understand why Walter would do that. She honestly has no clue why he would ruin his food like that. As a result, she openly comments on it; Walter immediately feels ashamed and puts his hands in his lap. Atticus shakes his head in disapproval at her and Calpurnia grabs Scout and runs her into the kitchen where a strict lesson is quickly taught, as follows:
Hush your mouth! 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—if you can't act fit to eat at the table you can just set here and eat in the kitchen! (24-25).
Scout is surprised at Cal's reaction, but she learns quickly that when someone is a guest in her house, they will be treated with respect and dignity. Scout didn't know to keep her opinions to herself and did what any curious kid would have done: she asked what Walter was doing and judged him for it. It's difficult learning that other people don't act like we do. Scout simply did what many kids would have done in her situation.
One other example that shows a child reacting to the world around him because he doesn't know what else to do is when Jem attacks Mrs. Dubose's flowers with Scout's baton. Jem had been keeping his cool for a long time when Mrs. Dubose would yell at him and Scout as they passed her house. With pressure coming from the whole community about Jem's father representing a black man in court, it didn't help that Mrs. Dubose went and yelled at him the following:
Not only a Finch waiting on tables but one in the courthouse lawing for ni**ers! . . . Yes indeed, what has this world come to when a Finch goes against his raising? I'll tell you! . . . Your father's no better than the ni**ers and trash he works for! (101-102).
After this comment, Jem goes to the store to buy a steam engine for himself and buys a...
baton for Scout. As they are walking back from the store and in front of Mrs. Dubose's house, something snaps in Jem's brain and he grabs Scout's baton, and uses it to chop off the tops of all of her camila bushes! Once the front yard is littered with leaves and buds, Jem breaks the baton over his knee, grabs his sister by the hair, and drags her home as she's screaming.
In the first example, Scout is being told to respect other people no matter how different they are, and in the second, Mrs. Dubose, an adult, does not show the same respect. It must be very confusing for the kids to be taught good things and then adults don't follow the same advice. Then, Jem must have felt so powerless bearing the weight of Mrs. Dubose's words against his father that he burst under the pressure. His child-like instinct was to react and he took out his hurt feelings on Mrs. Dubose's plants because he couldn't defend himself against her verbal attacks.
Clearly, Jem didn't know how to handle the situation at all. Later, he is forced to read to Mrs. Dubose for a month as compensation. But the fact remains that Jem is just a kid, too. He didn't know what to do to reclaim his honor against Mrs. Dubose's cruelty.