What is the theme in this passage?

As Joy reached her class, she noticed that Mr. Somers looked annoyed.
"And what's your excuse for being late today?" he asked, peering over the edge of his glasses.
"It was my mother," Joy answered. "She had to leave for Ohio this morning and forgot to wake me." Joy hoped her teacher would buy her
excuse.
"Really, now?" Mr. Somers commented as Joy entered the class.
"May I come in?" Bianca announced from behind Joy.
"And what is your excuse, Miss Temple?" Mr. Somers looked like he was used to this routine.
"It's my fault," Bianca replied honestly. "I woke up late."
"Well, make sure it never happens again. Go take your seat." Mr. Somers sighed.
As the girls moved to their desks, Mr. Somers interrupted.
"Miss Rodman, as punishment for your late arrival, you will be helping the drama club for the next two weeks. Either that, or you can go see the
principal"
"What? Why are you punishing me alone? Bianca's late too," Joy complained.
"Yes. But unlike you, she told me what really made her late," Mr. Somers said.
Joy glanced at Bianca as she flipped her hair over shoulders and grinned.