What is the plot of "Charles" by Shirley Jackson?

The basic plot of Shirley Jackson's short story, "Charles," is as follows: 

Laurie is a boy who is beginning kindergarten. His mother is the narrator of this story. Laurie comes home with stories about what a boy in his class has done nearly every day. The boy's name is Charles. Charles hits the teacher, bangs the see-saw onto the head of a classmate, and throws chalk, among many other socially unacceptable deeds. 

Laurie's parents begin to wonder about the type of influence Charles is with their son. Laurie's father states that it's better for him to learn now rather than later how to deal with these things, because there are bound to be people like Charles in the world. 

All the while, Laurie is showing behaviors at home that mirror Charles's behavior. He yells loudly more than once, spills his baby sister's milk, and speaks insolently to his father. One example of this is when he says "Hi pop, y'old dust mop." 

For a short time, Laurie reports that Charles's behavior improves, but soon he is back to his old antics. He tells a girl to say an evil word in class, and she does. Then, Charles becomes bold enough to say the word himself. 

Laurie's mother attends the PTA meeting and is desperate to meet Charles's mother. Laurie's father asks his wife to invite Charles's mother over for tea so he can "get a look at her." Laurie's mother scans the faces of all the mothers during the PTA meeting to try to deduce which one is Charles's mother.  

Later, Laurie's mother approaches Laurie's teacher. Laurie's teacher remarks "We're all so interested in Laurie." She shares that Laurie had some trouble adjusting, but that he's a fine little helper now, "With occasional lapses, of course." Laurie's mother asks about Charles. The teacher replies that there is no student in kindergarten named Charles.