Education Minister Hekia Parata is at the centre of a privacy complaint.
Dawn Laurence from Waitara High School wrote a letter to the minister earlier this year expressing her worry about plans to increase class sizes.
But the minister responded directly to the school's board of trustees.
Ms Laurence said she felt that breached her privacy and complained to the Privacy Commissioner.
The commissioner said she has spoken to the minister's office, which has agreed it should not contact a teacher's board if they are writing as a private person and not as an employee.