"They needed to finish high school in New Plymouth and we didn't want to disrupt them.
"As long as the fridge was stocked, they were fine and now they are both at university."
Michael is the sole teacher most of the time while Yvonne handles the administration and all the other tasks involved with running a small country school.
When they moved to the valley in 2013, the Bieleskis thought they might stay for two years but they have come to love the people and the valley so they are not going anywhere in a hurry.
According to the school's 2014 Education Review Office report, Michael is already a long-term principal - two others had come and gone since 2011.
The report commended Michael's level of engagement with school families and how he works collaboratively with students, parents and staff to develop values of care, attitude, respect and excellence.
The school work with local iwi, Nga Rauru on a number of projects including teaching te reo Maori and the Nga Rauru curriculum.
Staff have participated in learning te reo Maori, and Mr Bieleski teaches Maori lanuage and waiata as part of the curriculum.
A qualified early childhood teacher (among other things), Yvonne was hosting the monthly preschool and community morning tea on the day the Chronicle visited.
Local mums Alana Wright with son Jack (4) and daughter Lilly (2), Megan Belton with son Murphy (2) and Karen Rumble whose sons Jett and Tyler are already at school were in attendance.
All three said they have moved to the valley within the last decade and South African-born Karen moved there four years ago with husband Tim to establish Waitotara Valley Estate hunting lodge.
The morning tea spread is a mix of Kiwi classics - sausage rolls, scones with fresh cream and jam along with Karen's contribution of delicious sweet pumpkin pancakes.
"We had the annual pig hunt a few weeks ago and these three came first, second and third in the piggy back race afterwards," said Yvonne.
The deceptively petite trio each completed an obstacle course with a pig carcass on their backs.
"We had to go around the school grounds and up and down the playground slide without dropping them," said Megan.
Despite their remoteness, children at Ngamatapouri School do not miss out on digital learning thanks to a satellite dish on the hill.
The children happily shared their learning with visitors and senior, middle and junior pupils are working on assignments and exercises that support their other learning.
While younger students are playing spelling games or reading digital books, Brianna Wallace 12, was updating her blog posts of school events.
Michael said the digital learning enhances other classroom learning and is linked to other curriculum activities.
"It is about the devices being useful learning tools rather than replacing other ways of gaining information," he said.
Maraeroa Kauika-Tenison 12, is using editing software to put finishing touches to a film of flooding in the valley last year.
Michael and Yvonne forged closer links with the valley community during the floods, and the school staff room became a support hub and drop-off point for supplies flown in via helicopter.
"The community looked after us too," said Yvonne "the marae linked us to the generator that had been flown in and we were gifted a large meat pack to help us get through."
Michael kept in touch with families via email while they were isolated and sent links for children to complete online assignments while they could not get to school.
The scars on the valley hillsides are reminders of the flood and there is a fresh slip caused by recent heavy rainfall.
Despite a zero degree frost in Whanganui on the morning of our visit the valley was frost-free as we drove in and Michael said frosts are rare at Ngamatapouri.
"When I was interviewed for the job, I asked if there were a lot of frosts here and was told that the mists tend to keep them away."
It is still cold outside but that doesn't bother the school children who happily run barefoot around the school.
"Country kids," said Michael "they are happy to run around outside in all weathers."
The Bieleskis are supported in the running of the school by the Board of Trustees made up of parents and chairman Harvey Porteous.
Appointed by the Ministry of Education, Harvey is a former principal of St Johns Hill School and a long-time advisor to rural schools.
"People can get the wrong idea about my role," says Harvey.
"Because I am ministry appointed, they might think the school is under statutory management but it is a different kind of governance.
"Because the school has a small pool of families, they don't have the range of experience that parents at city schools have so I'm there to provide that governance experience."
Harvey said it is also about providing guidance for the principal as those who come to Ngamatapouri are taking on their first-time management role.
"There is a lot to learn and Michael and Yvonne have done a wonderful job of fitting in to the community."
Harvey generally visits around twice each month and said he enjoys the role.
"I wouldn't do it if I didn't enjoy it and it is a nice drive from Whanganui although I did get my car stuck in that new slip last week and I had to be towed out."
Michael also gets support from his release teacher Melody Wallace, who generally works on Thursdays and Fridays.
A past pupil at the school herself, Melody's own children Brianna and Harvey are currently attending Ngamatapouri.
And Yvonne who is an experienced deputy principal and reading recovery teacher also works (and volunteers) in the school covering whatever needs they have.
The Bieleskis sometimes leave the valley during the school holidays to visit daughter Sarah in Wellington who is in her last year at Victoria University completing a Bachelor of Science Psychology and Biology.
Later this year, they will fly to Dunedin for their other daughter Amy's graduation from Otago University where she is completing a Bachelor of Arts in Politics and Communication.
Michael goes ice climbing at Ruapehu and Taranaki whenever he can and they visit friends and family in New Plymouth, Tauranga and Auckland.
The couple say there is plenty to do in the valley though - they are actively involved in their beautiful, little local church, St Hilda in the Woods and they are avid supporters of Ngamatapouri Rugby Team.
There may be some future All Blacks currently attending Ngamatapouri School if past pupils are anything to go by because Glen Osborne and Israel Dagg both went there.
The Bieleskis say life in the valley is far from dull and surprising things can happen - when I called the school on Wednesday, Michael reported that he woke that morning to a Ngamatapouri frost.