Ms Sadler said students would be involved in environmental learning, building greenhouses and growing plants.
She said it was ridiculous for NZ First to suggest a school with 70 pupils and five staff would open with portaloos. A toilet block was being built and would be ready by opening time on February 10.
Teaching space would be in a temporary building for the first two months and buildings would be finished by April 10.
Tracey Martin asked Ms Parata to clarify what would happen to the land if the charter school closed.
Ms Parata said: "We can confirm that, as is the case with any school, if the school closes or in this case if the contract with the sponsor is terminated, then payment to the sponsor may be recovered through usual commercial processes."
The trust was one of five successful applicants named in September to run the first charter schools to be opened in February.
It plans to set up a bilingual secondary school known as Te Kura Hourua ki Whangaruru at Whangaruru, targeting Maori and Pacific students.
It will have an initial roll of 71 students, rising to 128 by 2015.
Ms Sadler is a trained secondary school teacher, and has been a national assessment facilitator at the NZ Qualifications Authority, a deputy and acting principal at an area school and a senior adviser at the ministry.