The Government's offer fell short of the 16 per cent over two years union members had sought.
Trish Hunt, a Fairhaven School teacher and member of the union's primary teachers' leadership team, said they were fighting for more resourcing for teacher recruitment, workload reductions and learning support for students with additional needs as well as fair pay.
She believed the mood in the room was generally supportive of striking.
"Some wanted to see us strike harder at the beginning."
The loudest clap of the meeting went to a teacher who called out that a three-hour strike would send a "weak signal to the Government".
"We should be going out for a whole day."
Hunt said the half-day strike was a step in an escalating process of action.
"We are mindful that we want to be considerate to our tamariki and our community."
Teachers were encouraged to rally support in their school communities.
A spokeswoman for Minister of Education Chris Hipkins said he could not comment while teachers were considering the offer under good faith bargaining.
Labour MP Jan Tinetti, who until last year was Merivale School's principal and a member of the union's national executive, said she could not comment on the negotiations.
She said, however, that it had been interesting to see the process from the Government's perspective.
"I know how easy it is to sit there and think that the people in Wellington don't value what we teachers do. I can assure them they are valued. But it is not an overnight fix."
The offer on the table
- Most teachers would get a pay rise of between 2.2 to 2.6 per cent a year for three years
- New teachers (in their first three years of teaching) would get 4.3 to 4.7 per cent increase a year for three years
- First-year teachers would go from $49,588 to $56,638, 24 months after the agreement was signed.
Source: NZEI Te Riu Roa