Because of Government funding cuts to the station's school in 2011, the nearest classroom the family's four children could attend was in Fairlie or Tekapo, nearly 80km away.
So the Grahams decided to reopen Haldon School with Paige, 9, Jack, 7, Madeline, 6, and Levi, 4, as the only pupils.
Levi is enrolled in the early childhood correspondence programme.
The school has a large collection of books, a small playground and even a uniform.
The children attend school via correspondence in Wellington and are supervised by their mother.
Emma Graham told the Herald it has been going very well so far.
"The kids are enjoying it a lot. I home-schooled them until February but now they all have the same teacher in Wellington.
"The kids wanted a uniform and luckily for us, a box was left over when the school was open earlier and we were able to use that."
The Correspondence School sends education packs for English, maths, science, art and more and the children follow a structured lesson plan.
Graham said they loved being the country's smallest school.
"It's the cutest little school and we are lucky that we get to use it. There are five other preschool-aged kids on the farm.
"If there are other families living on Haldon Rd who aren't on the station, it would be really cool if they joined us as well."
The children go to Tekapo School each Friday where they join in on lessons, which Graham said is a good way for them to interact with other people their age.
She said the move to Haldon Station from the West Coast has been good.
"It's great weather, the kids are loving it. The lake is practically on our doorstep. It has been a good move for us."
The average yearly rainfall in Hokitika is 2800mm, at Haldon Station, it is 300-500mm.
Station manager Paddy Boyd said it is great to have the school open again.
"It's just a wee one but that's all we need. It was pretty disappointing when we lost funding a few years back and we don't have a bus to take them to a larger public school."
Boyd said they have been trying to get Government funding for a paid supervisor in preparation for more pupils.
"We need the Government to front up and help us. We pay taxes and I think everyone should be entitled to an education.
"We have been left to completely pay for it ourselves."