The teacher's lawyer, Tae Wok Kwon, noted that the student teacher, who is British, complained only about the Korean teacher and a Chinese team leader and not about two other teachers in the room where she was placed.
"They might have different ways of Asian mothers of training their children. She might be prejudiced," he told the tribunal.
"She did not know [the teacher]. She just assumed she was one of the Asian women who was handling their children harshly. So she did not have personal knowledge at that stage, she might have presumed that.
"I don't say she is racist but she might have some ethnical prejudice."
The student teacher rejected the allegation.
"I am offended that that would even be suggested. I actually didn't know that [the team leader] was a person of Asian heritage," she said.
The student teacher said she saw the Korean teacher smack her daughter three times in quick succession.
Kwon said his client would say that her daughter was playing with water.
"She had to tell her not to do so, so my client went to [her daughter] and held her firmly and she told her off. [The daughter] was frightened and started crying. She did not smack [the daughter]," he said.
But the student teacher said there was no water involved.
"[The daughter] only cried after she was smacked and had her face pulled forward by her ear," she said.
Kwon asked: "When the child was crying, did anybody come to help her?"
The student teacher replied: "No, because she was in her mother's arms."
She said another teacher, who was standing next to her, "saw my face and said, 'It's okay, it's her daughter.'"
She later discussed this and other incidents at the centre with her lecturer and then rang the Ministry of Education about her concerns.
The team leader, who was not present when the first incident occurred, gave evidence that she saw the same teacher smack her son in the centre's playground after 3.30pm on April 5 last year.
"A little girl had built her structure, she went to show [the teacher]. [The teacher's son] had knocked it out of her hand. She cried. So [the teacher] smacked him, and he cried," she said.
"The other child was crying because her structure was broken. [The teacher's son] was crying because he got smacked by [the teacher]."
Asked to rate the smack's level of force on a scale from one to 10, she said it was "a two or three". She saw it from about nine metres away, but she could not hear any sound.
"It was not strong enough to make a sound, but it was strong enough to make him cry," she said.
The team leader said she did not stop the mother because "she was consoling him after what had happened, giving him a cuddle". Instead, she rang the office to report the incident. The centre manager, who was on her way home, came back to deal with it.
Kwon noted that the student teacher had also told the Ministry of Education that she was unhappy about inadequate induction to the centre and was uncomfortable about the way the team leader took an autistic boy to the toilet.
The team leader was not found to have been at fault because she followed correct induction procedures and an agreed plan for the boy's toilet training, but Kwon said the complaint must have put her under pressure.
"The complaint was made on her that she was not showing proper leadership, so she wanted to do something to make up for lack of proper performance, so she was looking for someone to be a scapegoat and that's why she exaggerated it to a smack," he said.
"She [the Korean teacher] patted him or touched him, but it was not a strike or smack."
But the team leader responded: "Why would he get upset if it was just a pat?"
She said she later questioned other teachers who were in the playground at the time, but no one else had seen the incident.
The Korean teacher will give evidence when the hearing resumes.
