The Education Minister has referenced anti-apartheid protests when calling for the PPTA to drop its ban on working with people involved with charter schools.
A member of the audience at the education union's annual conference in Wellington walked out after the comments, which Hekia Parata later stood by.
Ms Parata had delivered a speech covering a wide range of education issues, and during a question and answer session she was asked about charter, or partnership, schools.
She said she was extremely disappointed that a student teacher who had worked at Te Kura Hourua O Whangarei Terenga Paraoa, a charter school in Northland, subsequently lost his placement at Tikipunga High School.
The PPTA's position is to limit where possible professional interactions with charter schools.