But to put a human face on the nearly 7000 children the research team realised they needed ways of illustrating the myriad family situations. One of the more intriguing exemplars, in research-speak, was created by Lynne Townsend from the Museum of New Zealand Te Papa. She collected objects from seven of the children when they were 3, to help see the children's world from the children's perspective via the objects that matter to them. The second wave of Collecting Childhood is now under way with the children turning 7.
One of the children is Austin Wang, with his mother Ying Jia Li (she also uses an English name, Kili) and father Wilson Wang. Austin's parents and grandparents emigrated from Shenyang city in northeastern China, and joined the study when Ms Li was pregnant with him. "We were very happy to join at the beginning," she says.
"But later on we found it very meaningful. They share the research and communications, we're very lucky to be one of the families.
"I came here when I was 22, and my childhood was totally different. We had lots of homework, focus on study, no time for after-school classes.
"My parents couldn't afford for me to play piano. So we try our best to support Austin."
It is no surprise then that the objects the youngster presents to the Herald (apart from his nerf gun) are a slew of certificates from his busy life.
The young man, who his mother says can't sit still, has trophies and certificates for player of the year for his football team, which he attributes to being good at scoring "and when I fell down I got up again". There's a Room 8 Superstar award from his Point View school, excellence awards for piano playing, swimming wins, a second stripe on his Tai Kwon Doe belt. He's also fitting in summer football, basketball and running. Mother and son are looking forward to his 7-year- old interviews soon.
Dr Morton admits that the research programme, designed about 10 years ago before social media was mainstream, now needs constant rethinks.
In this year's round, the 45 field interviewers are keen to see what effect screen time, both TV and digital, has on child development.
"It's not just about 'let's limit screen time', we need to find out why people are using it as a babysitter. People lead complex lives, what other reasons are operating? At 3 years the [collecting childhood] children didn't have anything digital, so we'll be curious this time around to see what they have ... The objects are going to link us to the important stuff in their lives. This is our first time to engage with the kids on their own, telling their own stories, with their own identities. Seven is an important age."
Like all studies, there are numerous ethical guidelines, but Dr Morton admits that one of her scarier audits begins this year, when a panel of the participating children will help them design their study approach.
"We are so privileged to interact with these families, bring these stories together," says Dr Morton. "Every one of those voices are important, people can be heard."
See more of Austin and the six other children's collections at collections.tepapa.govt.nz/topic/8828. For the study, see www.growingup.co.nz