The researchers found children were resilient and adaptable, but lockdowns also presented emotional and social challenges. Equity issues also came to the fore, with stark differences in device access and mental health.
Growing Up education lead Dr Kane Meissel said the real surprise was how positive the findings were for the vast majority of children.
Of the almost 2500 children who responded to the May 2020 survey, around four in five were in very good health, while a similar number reported having a good time with their family in lockdown.
Earlier studies of locked-down Kiwi kids had been positive but were mostly small scale and more qualitative, Meissel said. Researchers had been a "little sceptical" whether such good results would show up in the Growing Up survey, one of the largest in the world.
In fact, the vast majority of kids had found lockdown more positive than the researchers expected, he said.
However, Meissel said the declines in school satisfaction were very significant and widespread. More than three-quarters of the children, who were aged 10 and 11 last year, were less satisfied with school than they had been at 8 years old.
Involvement in things like baking, housework or sports - even if not school-related - were important predictors of school satisfaction.
Having a bubble of six or more people was one of the strongest protective factors helping children stay satisfied with school. This also helped protect against anxiety and improved wellbeing.
Anxiety scores were highest among European children and lowest among Pacific children, closely followed by Asian children. Tamariki Māori experienced the largest drop in school satisfaction since they were eight, while children of Asian and Pacific descent saw the smallest relative drop.
Meissel said one reason for the positive Pacific scores could be that these children were likely to be in bigger bubbles, meaning more connections and lots of family involvement in their schoolwork.
The smallest bubbles of just two people - usually a mother and child - had significant drops in school satisfaction.
Screen time also shot up, with a resulting drop in satisfaction. On average children spent almost five hours in front of a screen during lockdown weekdays, with more than two-thirds using devices every day for school.
Children from more well-off families had more weekday screen time - and longer screen hours were linked to less school satisfaction.
That mirrored other recent research, Meissel said.
"Dumping everything online is never going to be a great experience for kids. And as we know, you go from Zoom to Zoom, you just get exhausted. It's the same for a lot of children - they don't want to be online."
Despite the downsides of screen time, there were also equity issues for children with no device or less connectivity. All children should have good access to online schooling in future, Meissel said.
There were also concerning findings around mental health. Around two in five had symptoms of depression or anxiety and a similar number worried about finances.
Nearly half felt they didn't have someone they could talk to often about their feelings, and 13 per cent said they rarely felt listened to by their caregivers. One third never or almost never talked about their feelings.
There were some caveats. It's possible the results were skewed by who responded to the online survey; and it's also not yet clear how much changes like school satisfaction are due to the pandemic or part of getting older. More work will be done in this in future research.
WHERE TO GET HELP:
If you are worried about your or someone else's mental health, the best place to get help is your GP or local mental health provider. However, if you or someone else is in danger or endangering others, call police immediately on 111.
OR IF YOU NEED TO TALK TO SOMEONE ELSE:
• 0800 543 354 (0800 LIFELINE) or free text 4357 (HELP) (available 24/7)
• https://www.lifeline.org.nz/services/suicide-crisis-helpline
• YOUTHLINE: 0800 376 633
• NEED TO TALK? Free call or text 1737 (available 24/7)
• KIDSLINE: 0800 543 754 (available 24/7)
• WHATSUP: 0800 942 8787 (1pm to 11pm)
• DEPRESSION HELPLINE: 0800 111 757 or TEXT 4202
• NATIONAL ANXIETY 24 HR HELPLINE: 0800 269 438