In Harper Lee's To Kill a Mockingbird, there are several mistakes Miss Caroline makes the first day. First she tells Scout not to let her father teach her to read or write anymore, causing the child embarrassment and disappointment.
In terms of knowing (or not knowing) her students, Miss Caroline makes two major mistakes based on her unfamiliarity of the economic circumstances with which her students live.
First, she tries to force Walter Cunningham to take money for lunch when there is no way he could pay the debt back—Miss Caroline has no point of reference regarding the poverty in which they live. These are children of southern farmers—hit especially hard by the Depression—that can only pay in goods rather than cash, barely squeezing by. As Scout tries to explain: "They don't have much, but they get along on it."
"Miss Caroline, he's a Cunningham." [...]
Scout knows quite well about Walter's difficulty with Miss Caroline's offer of money. She recalls Atticus doing so work for Walter, Sr. Scout and the other students are all familiar with the hard life of the Cunninghams. In fact, quite a few among them deal with the same difficulties.
He didn't forget his lunch, he didn't have any. He had none today nor would he have any tomorrow or the next day.
Once more Scout tries to reason with Miss Caroline:
The Cunninghams never took anything they can't pay back. [...] You're shamin' him, Miss Caroline. Walter hasn't got a quarter at home to bring you, and you can't use any stovewood.
Miss Caroline cannot follow this line of reasoning that makes perfect sense to Scout and the other children. In light of this, she punishes Scout by tapping her hand several times with a ruler and sending her to stand in the corner.
The second mistake Miss Caroline makes is in telling Burris Ewell to go home to wash his hair and take a bath. Burris nastily announces that he has only come for the first day of school—as he has now for the last three years—and that he's leaving anyway. Miss Caroline (not knowing the disposition of the Ewells) asks Burris to sit down. In response, the youngster threatens the teacher:
Miss Caroline said, "Sit back down, please, Burris," and the moment she said it I know she has made a serious mistake. The boy's condescension flashed to anger.
"You try and make me, missus."
Little Chuck Little got to his feet. "Let him go, ma'am," he said. He's a mean one, a hard-down mean one. He's liable to start somethin', and there's some little folks here."
As polite as Little Chuck is, he is not one to be pushed around either. As Burris turns toward him, Little Chuck's hand makes its way to his pocket, where the reader can infer there rests a knife.
Watch your step, Burris...I'd soon as kill you as look at you. Now go home.
As Burris leaves, he hurls back insults at the teacher, departing only after making certain he has caused her to cry.
If Scout's ability to read and write as a first grader caused Miss Caroline to be come distressed, the reader may infer that Burris' insolence and menacing behavior, as well as Little Chuck's threatening protection of Miss Caroline, would be cause enough to make the woman think twice about teaching first grade in Maycomb. Obviously her life in Alabama did nothing to prepare her for the diverse population of her new class. Not only is the reader able to understand Scout's frustration with school, but also we can interpret how difficult it is to teach in this community and how ill-prepared an outsider is to deal with the specific circumstances the people of this town face on a daily basis.