In the story "The Doll's House," by Katherine Mansfield, the reactions of the school teacher toward the Kelvey sisters essentially describe someone who has very little compassion toward those who need it the most. This a sad realization, especially when the reactions are coming from someone whose profession is to nurture and educate children.
Her reaction toward the girls is very cruel, to say the least. The main issue is that hers were not just spontaneous reactions of which she had no control. Instead, her actions against the Kelvey girls, particularly the youngest Kelvey, are pre-meditated and done with the purpose of gaining the support of the other kids.
...the teacher had a special voice for them [the Kelvey sisters], and a special smile for the other children when Lil Kelvey came up to her desk with a bunch of dreadfully common-looking flowers.
This means that the teacher had a habit of openly mocking Lil Kelvey by changing her voice in a way that showed that she (the teacher) merely pretended to be moved by the gesture of the little girl of bringing flowers to her teacher.
To be more descriptive, the teacher essentially changed faces. She would show a fake expression of gratitude toward little Kelvey for the flowers, and then she would sarcastically look at the rest of the kids to make them aware of what she is doing. This is no different than what a comedian does when he has to pretend to like something in a funny skit, and then looks at the audience with a mocking expression to let them in on the joke, so that it would provoke humor.
The problem is that she was doing this to make one of her own students, one of the poorest and most needy students, look bad in front of the other kids. In other words, the teacher acted like yet another bully, even though she is the adult in the room.
The attitude of the teacher towards the Kelvey girls is indicative that she, too, harbors feelings of dislike and rejection toward the Kelvey sisters because they are poor, unkempt, and uncared for.
Judging by the actions of the teacher, she is quite condescending with the girls. She looks down on them in a way that mirrors the looks and actions of the other girls at school. She is haughty, supercilious and she even humiliates the girls by treating them in an entirely different way that she treated the others.