Auckland principals say they are well-prepared for a return to home learning this week, but they warn that some children will fall behind.
The alert level 3 lockdown is keeping a quarter-of-a-million children out of the classroom, and principals are worried it will be extended.
At alert level 3, schools are open only for children of essential workers and those who cannot stay at home.
Olivia Fox, 15, told RNZ her school sent students home yesterday and planned to start online learning today.
"I was pretty stoked, I'm not going to lie, because I have a test," she said.
However, she said learning from home could be challenging.
"I'm not looking forward to it, but I think it will be fine because we've experienced it before."
Caleb Patterson, 13, said he was disappointed because the lockdown had cancelled a school cross-country race, which he had been looking forward to.
He said learning at home was not as good as being in a classroom.
"It's a lot easier to learn in a classroom because you can just ask a teacher."
At Balmoral School, principal Malcolm Milner said the quick closure of the school had gone smoothly but the sudden change was eerie.
"We had no one come to school today. It's pretty quiet and it's pretty unsettling when you have more than 880 people here and suddenly there's only eight of you here. So it's like a ghost town really at school," he said.
Milner said teachers were getting work to their pupils, but keeping it low-key so they did not alarm anyone, and they were well-prepared to go back to online learning.
However, he cautioned that teachers' classroom programmes were often quite different to what they would do online.
The principal of Randwick Park School, Karen McMurray, said the return to distance learning had gone well.
"It's pretty good actually, we're all set up ready to go. We've got online learning that we can reactivate, we've been doing online homework since lockdown," she said.
"A lot of our children don't have internet access or devices so we've got the hard copies ready to go and the resources to go in them should we go further than Friday."
McMurray said the school had been preparing for a return to home learning because it felt another lockdown was inevitable.
She said she was worried about the impact of another lockdown on some children.
"We've also started putting in extra support and literacy mileage for our children who didn't do a lot of learning during lockdown previously," she said.
The president of the Auckland Secondary Principals' Association, Steve Hargreaves, said principals were disappointed that community transmission had caused schools to close again.
"Schools were just hitting their stride again. All the extracurricular was up and running, and the learning programmes were back in full-swing, planning for secondary tournament week and things like that. So to then have a step back, it was a bit of a body blow," he said.
Hargreaves said he saw some students at his own school, Macleans College, just before the lockdown began at midday on Wednesday and he worried that it would affect their learning.
"You can just tell in their mood that they're down, they're feeling a bit upset by it all. And I guess the next thing is I don't think it's going to be three days. Now I know that's just speculation, but I think the two things, the length of time away from class and then just the effect on the mood and the confidence and the willingness to go on will have an effect on the students' learning," he said.
Hargreaves said teachers were good at encouraging their students, but it was more difficult to do via the internet.
However, he said schools were better prepared to provide home learning for their students.
"We're feeling pretty confident actually. We know we did it well last time, schools across the country handled it incredibly well, we learned a lot, teachers went on this enforced period of professional development and came out the other side with a whole new bunch of tricks and skills and knowledge about remote learning and digital strategies and they're all ready to be rolled out again."