Family members joined the pupils to work on assignments, including a challenge to build the tallest, sturdiest balloon tower.
"If we involve the community, there's a higher chance the learning will go home," says Jason. "We know from our academic data that the kids are achieving really well here. But we don't want it to stop at the gate. Learning is everywhere so we want that message to go home."
"Henry Hill works for the kids," says Charlene Gannoway, who has three grandchildren at the school. "It's a family environment. The teachers are very friendly. It feels comfortable here."
Charlene's youngest son attended the primary school several years ago before moving on to Napier Boys' High School.
"I wish Henry Hill was like this when he was here," she says. "The kids are having fun. They're learning. It's perfect."
Aira Ormond, who was visiting her grandson, was equally impressed with what she experienced at Henry Hill.
"There's no Pakeha, there's no Maori - it's just kids going to school."
Both women admit the learning environment has changed dramatically since they were students. Demonstrating that progress, Jason says, was one of the reasons for organising Whanau Day.
"We're sharing with our families, because that's not how it was when they were at school," he says. "Then it was set subjects, sit down, the teacher will tell you what to do, you will listen.
"But that's not how it works anymore, so we try to share that with the families so they have a better understanding of what we're doing and understand what the kids are talking about so they're not on different planets anymore."
The lunch break was followed by tabloid sports, where the pupils and adults moved through a series of novel activity stations. Jason was pleased to see the positive reactions from the family members.
"I'm absolutely rapt - couldn't be happier," he says. "What it tells me is that we do have an engaged community.
"We're not doing this to tick a box or collect data. This is just about engaging our families and hoping the learning carries on at home."