Miss Caroline has been a student of theories of education to which she fervently believes she must adhere.
Miss Caroline Fisher does not notice that the class fidgets during her reading, and she displays her lack of insight when she fails to recognize that most of the class knows the alphabet. Her negative reaction to Scout's ability to read demonstrates that the woman is a programmed product of her educational institutions. It is also irrational that Miss Caroline believes in experiential learning, but when Scout demonstrates her experiential learning, she is critical of it, telling Scout to inform her father not to teach her.
Clearly, she feels threatened by the precocious Scout. This is why she asks Scout to read the stock market reports--an irrational request made just to cause Scout embarrassment. However, she is defeated in her attempt because the child is able to read such reports, and so Miss Caroline embarrasses herself. All she can do is tell Scout to have her father not teach her any more.
Atticus displays the best understanding of Miss Caroline's treatment of Scout when he talks about education in his summation at the trial of Tom Robinson:
The most ridiculous example I can think of is that the people who run public education promote the stupid and idle along with the industrious--because all men are created equal, educators will gravely tell you, the children left behind suffer terrible feelings of inferiority. (Ch.20)
Not wanting the other children to be embarrassed by Scout, perhaps, or not wanting any student to get ahead of the group, Miss Caroline makes efforts to embarrass Scout into being quiet. Scout does not fit neatly into a box; no one in first grade is supposed to know how to read so well or, certainly, to write in cursive. She does not want Scout to possess more knowledge than the average first-grader. After all, she lacks experience and seems to lack the imagination to consider what to occupy the girl with if she already knows the things that others will take a year to learn.