Secondary school teachers are on strike on Wednesday.
The action by about 16 thousand union members will affect almost 280,000 students at about 300 schools.
Their union, the PPTA, has exempted Canterbury schools from the strike, but many schools are expected to close in other parts of the country.
The strike is over stalled negotiations on a collective agreement. The PPTA wants a pay rise of 4%.
The Ministry of Education has offered a pay rise of 1.5% this year and a further 1% next year.
It says it will not amend its offer until the union returns to the bargaining table and indicates the priorities in its 46 claims.
The strike is the first in eight years.
PPTA defends claim
The Post Primary Teachers Association defends the 4% pay claim by secondary teachers as moderate.
The ministry says it is not realistic.
But PPTA president Kate Gainsford told Morning Report that 4% will still not bring New Zealand in line with the other countries that it competes with for personnel.
She said the Government has failed to respond to any of its non-pay related concerns about class-size, health and safety, and workload.
More to come - NZEI
Primary school teachers are also negotiating.
Radio New Zealand's education correspondent says it appears they are not happy with what the ministry has offered them, the same as secondary teachers.
Their union, the NZEI, on Tuesday expressed dissatisfaction with the ministry's offer.
Union meetings will be held in mid-October.