What are two examples of Laurie's misbehaving at home?
In "Charles," most of Laurie's misbehavior at home is disrespect and bad manners. Since we only see him interacting with his parents, this is directed toward them. There are several examples in the story.
The narrator, Laurie's mother, describes how he comes home from his first day of school,
...the front door slamming open, his cap on the floor, and the voice suddenly become raucous shouting, 'Isn't anyone here?' (1)
Slamming the door, throwing his cap on the floor, and disrespectfully shouting in the house are all clearly bad behavior.
Additional instances of Laurie's bad manners and disrespect occur at the dinner table that night. His father asks him what he has learned and,
Laurie regarded his father coldly. 'I didn't learn nothing,' he said (1).
We are told that he was speaking with his mouth full during this conversation, and then,
Laurie slid off his chair, took a cookie and left, while his father was still saying, 'See here, young man' (1).
So, Laurie is disrespectful to his father, speaks ungrammatically, probably deliberately, speaks with his mouth full, does not seem to finish his dinner but takes a cookie, nevertheless, and leaves the table without asking to be excused, while his father is still speaking to him.
These may all seem like minor infractions, but it is clear that the "sweetvoiced nursery-school tot" (1) has come home a very different child!