The short story "Charles" by Shirley Jackson is about childish imagination, adults stereotypes and many other plot lines and ideas. That's the way Shirley Jackson sees the world, it is complicated, it has multiple dimensions.
The son of the narrator started to go to school (started kindergarten). Just a day ago his whole world was home and family. This change is how his mother estimates the new stage in their life:
"I watched him go off the first morning with the older girl next door, seeing clearly that an era of my life was ended, my sweet-voiced nursery-school tot replaced by a long-trousered, swaggering character who forgot to stop at the corner and wave good-bye to me."
Shirley Jackson wrote this passage using an ironical style. She described a quite recognizable situation, the parents, whose children passed through this line, would remember this milestone: their child becomes a part of society. The author told the readers how the son brought home the new impressions every day, how indifferent the parents were: they perceived the actions displaying curiosity as if they were watching the TV-news.
I'm not going to revile the end of the story: let's keep intrigue. This is the link for the text of this story; it is a good subject for discussion: