"I came in late from playing touch...instead of disturbing the class that's already working, I just grab my books, sit down'."
When her son sat down next to his friend, the other teenager did not look up. Seeing this, the teacher assumed he had been intimidated, Ms Fox said.
"I demanded that this teacher never taught my son again, and shifted his math class where the teacher treated him with respect and developed a relationship with him. He went on to pass his next maths achievement standard with excellence."
In 2014, a University of Auckland masters candidate said she was shocked by the responses of some teachers she interviewed for her thesis, which found teacher expectations were highest for Asian students, followed by Pakeha and Pasifika.
Expectations for Maori were much lower, the research found, despite Maori students' actual achievement being equivalent to that of Pasifika students and that 20 per cent were achieving at above-average level.
Ms Fox, who raised her son's experience during debate on legislation that will extend youth welfare service to older teenagers, said such prejudice was widespread, and served as an example as to why extreme care was needed when identifying "at risk" youth.
Many young people were up against a school system where prejudices were held by "people who do not deserve to be standing in front of those students", Ms Fox told Parliament.
"That's not all the teaching profession by any means, but this is an example, and I could point to 100 of them where prejudices against young people have inhibited their learning, where they have fallen out of the system."
Those sort of people would go on to be the type of young people targeted by the law change being debated, she said last night.
The legislation would extend the youth service programme to at-risk 18- and 19-year-olds, as well as all 19-year-old parents on welfare.
People in that age group will be assessed when they apply for a benefit and those judged at-risk of long-term welfare dependence will receive youth service support.
Teen parents will be obligated to attend a parenting course, enrol their children with a Primary Health Organisation and have them attend early childhood education, and complete health checks.
The youth service programme provides wrap-around support for young people, who can receive parenting advice and help to budget, pay bills and get into education.
The Green Party - the only party to vote against the legislation - has raised concerns about the risk of arbitrary and unfair decision making, and young people feeling stigmatised and resentful.
The Maori Party, Labour and NZ First have similar concerns, but supported the legislation.
Ms Fox, who before entering Parliament worked in Kohanga Reo, as a teacher and with the Ministry of Education, said she had spoken with Social Development Minister Anne Tolley, and had been told changes could be agreed for the upcoming committee stages.
"We understand targeted services...but we cannot blanket-ly say to a group of people just because you walk like a duck, talk like a duck, you must be a duck."
The Social Security (Extension of Young Persons Services and Remedial Matters) Amendment Bill passed its second reading last night 107 to 14 votes.
Ms Tolley said the legislation would make a long-term difference to the lives of young people.
"We've heard from providers that it's frustrating they have to stop working with young people when they turn 18. This bill will allow them to continue to assist their clients for longer to gain the skills they need to succeed."