The biggest clue that Laurie is in fact Charles is how Laurie seems to change so quickly from his mother's "sweet-voiced nursery-school tot" to "a long-trousered, swaggering character who forgot to stop at the corner and wave good-bye to me."

It is this swaggering character that they often witness at their dinner table. He spills his sister's milk, talks insolently to his father, uses bad grammar and gets up from the dinner table in the middle of a conversation without excusing himself. From the beginning, his behaviour and attitude is similar to the characteristics he describes in Charles.

There are less obvious clues in the text as well. For example, at the beginning of the story, he initially finds it difficult to look his parents in the eye when talking about Charles's behaviour, suggesting, certainly in retrospect, that he is trying to hide something. He then has to pause to think when they ask for Charles's name, suggesting that he is making the name up.

The final clue is how much a kick Laurie seems to be getting from the attention his parents are giving him. He may start off unable to look at them, but as time goes by he is either shouting Charles's name before he reaches the door or saying his name with an enormous grin. This all suggests that in recent times, since the arrival of his baby sister, his parents have not been so attentive to his needs.

The first clue that there will be some significant play on the idea of Laurie/Charles’s identity is in the opening paragraph when the mother tells us how significant a moment of change it is to see

my sweet-voiced nursery school tot replaced by a long-trousered swaggering character...

In other words, the first day of kindergarten brings a transformation that “replaces” the Laurie she thinks she knows with a “character” she barely recognizes.

Although this change is immediately apparent, once Charles enters the story the mother seems to notice Laurie’s behavior at home less and less. It’s as if the fictional Charles becomes much more interesting and attention-grabbing than the actual boy at home and school, which is typical of Shirley Jackson’s moral world in which the children put the adults to shame and the adults get the comeuppance for their assumptions and obliviousness.

Another hint comes when the parents ask about the identity of the troublesome classmate and Jackson tells us “Laurie thought” before replying, “It was Charles.” Jackson doesn’t suggest that Laurie has to recall or remember the name of the boy, but rather that he invents it, either pulling it out of the blue or having already decided before. Either way, we see Laurie is an excellent and natural liar but gets his parents so hooked on his daily reports of Charles’s mischief that they become increasingly blind to their actual child’s behavior.

Jackson is implying that it’s often impossible for parents to see their own children in a negative light, even when the clues are plainly evident. The deeper we see Laurie’s parents pulled into the Charles drama, the more Jackson heightens the suspense towards the big reveal which will contain the story’s tone of dark humor and puts some egg on the silly parents’ faces.

In Shirley Jackson’s story, the title character Charles becomes a fascinating subject for Laurie, a boy starting school. The author offers numerous clues to foreshadow the undeniable conclusion that the two boys are one and the same person. When Laurie first discusses Charles’s rudeness with his parents, he is hesitant and evasive. Soon Laurie’s behavior starts to change, as he goes from polite and caring to insolent and inconsiderate. Some specific things that Laurie tells his parents Charles had done are the same as or similar to his new attitudes and actions, such as yelling. Although this gradually accelerating transformation from peaceful to aggressive concerns his parents, they fail to realize their son’s deception.

The extreme changes in Laurie are out of proportion to the effects that starting school would typically have on a young child. Laurie seems to be very uncomfortable with the new environment in which he must function almost every day. Initially in telling his parents about the other boy, he is tentative and seems to be improvising. He does not immediately provide the boy’s name and avoids eye contact while lying to his parents. Laurie shows increasing boldness not only in misbehaving at school but in interacting with his parents. A once well-behaved boy becomes rude and aggressive, insulting his parents and physically assaulting other children at school.

The author included some clues in the story that help the reader to believe that maybe Laurie and Charles are the same person. For example, on the first page of the story, Laurie speaks to his parents about Charles however he is not looking at them, he is instead "addressing his bread and butter." When his parent's ask about the boy's name, the author states that Laurie has to think about it for a few minutes before answering. Immediately following this exchange, Laurie's dad asks him a question what the teacher did in response to Charles misbehavior but instead of answering, Laurie slides down off of his chair and walks ignoring his father's question. This evasiveness provides the reader with clues that something is not "right" with Laurie's story.

On the second page of the story, the author writes that Laurie came home late full of news about Charles. In Laurie's tales of Charles however, we find out that Charles was so bad that he had to stay after school. The mother does not appear to put these clues together but they are there for the reader. The final clue in the story is when Laurie's mother meets with his teacher, mentioning Charles and the trouble he causes in class. The teacher replies that there is no Charles in class.