Decisions about school closures and childcare support during the teacher and principals strike will be up to each individual board.
The 50,000-strong principal and teachers union NZEI Te Riu Roa has voted to extend a planned three-hour strike on August 15 to a full day.
NZEI lead principal negotiator Louise Green said all teachers and principals who were members of the collective agreement would be on strike that day.
Some schools would have to close for the day, but that decision was up to each individual board of trustees, she said.
"Different schools will be doing things, but it will be the individual boards that will make those decisions."
Any support for parents who could not get time off work or alternate care provided was also up to each board, she said.
"Many boards have already given warning to families about a potential strike, last term."
Green said extending the strike to a full day sent a stronger message to the Government that there needed to be better investment in education.
"Teachers and principals need to have time to teach, time to lead, and be valued for the professionals that we are. And all children need to get the support they need to thrive at school.
"We had a clear message from members at the paid union meetings and from feedback and surveys.
"It is 24 years since educators have gone on strike and this is not an action we are taking lightly."
A group of parents outside Freemans Bay School in Auckland this morning said they supported the strike action.
Emily Ansell said there was not enough support for teachers.
"We have been trying to get a teacher aid for my son. I appreciate teachers have so many children in their classes, they can't give individual help to one child if they have special needs."
Ansell said she would work from home that day to look after her son.
Glen Barnes said he and his wife were self-employed, so could look after their children at home during the strike.
"Teachers don't get paid a massive amount, and living in central Auckland is super expensive."
Kristina Kulma said teachers and principals needed better wages to make the profession more attractive.
"They need to be able to attract a better calibre of students to training college, and give the profession more status."
Lead NZEI teacher negotiator Liam Rutherford said public opinion polling showed strong support for more taxpayer dollars being spent on education, including a significant pay increase for educators.
"The National Party's u-turn on teacher pay and new desire for smaller class sizes means there is now no political opposition to addressing the crisis in education."
The decision for the full-day strike comes after NZEI and the Ministry of Education agreed yesterday to enter mediation over collective agreement negotiations.
The Ministry of Education had offered to increase pay, in the majority of cases, by between 2.2 and 2.6 per cent a year for three years.
The offer was a far cry from the 16 per cent increase teachers felt was needed to retain and recruit staff.
Ministry of Education Deputy Secretary of Early Learning and Student Achievement Ellen MacGregor-Reid said both parties wished to explore every possible avenue to reach an agreement.
"We value the work principals and teachers do and progressing these negotiations is a priority."
NZEI president Lynda Stuart said the union agreed to enter mediation "in an effort to explore all avenues".
"Negotiations are ongoing, and we are entering into the mediation in good faith," she said.
"Any outcome of the mediation will be taken back to NZEI members for their consideration."