But perhaps its the words of the man himself that sums it up best: "It's great memories at a wonderful school."
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Teaching wasn't the future Murray Armstrong's parents had in mind for him.
Armstrong grew up on a dairy farm in the Waikato, near Te Aroha and Morrinsville, and went to Springdale School.
After leaving Te Aroha College it would have been natural to slot into a life of dairy farming.
Armstrong's father suggested he get experience by working on a farm in the South Island, not realising it was setting him down a path that would eventually take him off the farm and put him in a classroom.
At the farm, a University of Canterbury student was working part-time to earn a bit of extra cash. He and Armstrong got to talking, and soon new ideas were blossoming in his mind.
"He told me all about university - I thought, 'I'll go to university'.
"I remember my father saying 'In that case, go to Massey and be a vet'. I enrolled at Canterbury, did English, geography, history and politics."
The appeal of Canterbury was the chance to check out the South Island, which he did by discovering most of the hikes and trails all over the island.
In 1974, Murray Armstrong was offered a job at Tauranga Girls' College, teaching geography.
His lucky break came during a Post Primary Teachers Association (PPTA) conference in Wellington in August of that year. Armstrong was the president of the students' association at teachers college and had been asked to speak.
Seated next to him was Joy Drayton, the principal of Tauranga Girls' College.
"She wanted to know what I was intending to do the following year. I said I was waiting for jobs to come up so I could have a look, she said to take a look in September and there will be a job for you."
He was hired - on one condition.
"She called me into the office on the first day. She had a request - that I had to have a haircut."
Off went his shoulder-length locks.
Was it hard to say goodbye to his hair?
"No. I didn't want another Sampson story though."
There were different dress standards in those days. The men wore ties in winter and some of the senior staff even wore their academic gowns.
The gradual move to more casual dress wasn't the only change at the college during Armstrong's four decades.
Some of the biggest changes are the students themselves.
"They stay at school much longer. For many students, once they were 15, or 16 at a pinch, they were gone.
"One of the big differences now is the bulk of students stay on for five years. We've had to develop a much more diverse curriculum to cater for the range of people who are wanting to stay at school."
Back then, the ones who stayed until Seventh Form (today's Year 13), were the ones who were destined for university, which meant all the senior subjects were academically based.
Staying around longer also meant more opportunities for leadership experience for the girls.
"There's a whole lot more older kids floating around the school than there used to be."
He's also seen some major changes to New Zealand's education system.
The three biggest changes in his time? Tomorrow Schools, the introduction of NCEA, and technology.
Technology, in particular, has made a big difference to teaching history. Research is much easier these days with the internet, which has also made history "a lot more visual".
Watching a YouTube video of Martin Luther King Jr's famous speech can be far more powerful than reading it in a book.
Even better than YouTube, though, is actually being there.
An international competition ignited Armstrong's passion for teaching on location.
In 2002, Armstrong took a group of students to the United States for the Future Problem Solving competition after becoming the New Zealand champions.
They finished seventh, a pleasing result (except for losing to the Aussies), then took off exploring for the remainder of their time, joining a crowd of 80,000 at a visit to Yankee Stadium and waiting in line for discounted tickets to a Broadway show.
This was the first of many overseas trips with students, including Russia, Poland and Berlin to study the Cold War and Russian Revolution. Their group was believed to be only the second school group from New Zealand to go on a curriculum trip to Russia.
"Everything in Russia worked like clockwork. Russians are incredibly efficient.
"We were blown away by that."
Another trip traced the footsteps of young Kiwi men and women in Europe in World War I, including an incredibly poignant trip to Passchendaele, where so many New Zealanders lost their lives.
Visiting the United States in April to learn about the Civil Rights movement was to be his final school excursion.
Over to Montgomery, Alamaba, they went, visiting the church at which Martin Luther King Jr was a pastor, and spending hours at "amazingly interactive" museums associated with the civil rights movement.
"It was just magic."
No trip to America can be complete without the mandatory visit to Times Square, which the kids "just loved", and a meal at Hard Rock Cafe.
It was a memorable way to mark his last year at Tauranga Girls' College.
These trips made up some of his best memories of his time at the college but his career highlights were much closer to home.
After a good think, he picked two.
Fittingly for a history teacher, they were both related to historical events: The 150th anniversary of the Battle of Gate Pā and the World War I centenary commemorations.
Both were a chance for Armstrong to involve the whole school in his love of history.
He nods in the direction of Gate Pā Memorial Reserve, less than a kilometre away on Cameron Rd, an acknowledgement to the history below our feet.
That physical connection to the battlefield made the battle's commemoration an important one for the school, particularly its Māori students.
In the staffroom, Armstrong points to a newspaper clipping pinned to a notice board with a photo of five students, one of whom is holding one of those large cardboard cheques, all of whom had Māori ancestry.
The $750 giant cheque was for a student whose speech on surviving the battle was so powerful, it earned her the right to speak with Willie Apiata VC at a formal dinner.
It's moments like these that made the commemoration so memorable.
"There were competitions throughout the community and our students participated in those.
"That had a really, really big impact on a number of our Māori students.
"At the awards ceremony, it was Māori student after Māori student."
The following year was the major year of the World War I centenary events.
Armstrong came up with a plan and divvied up tasks between different departments of the school.
He planned to create a Field of Remembrance for the 110 men from the Tauranga area who didn't make it home, then hold a memorial service with the community.
He lists the minutiae of pulling it together:
"I got the woodwork girls to make the crosses, got the girls in the art department to paint them, got the social science kids to research the names and ranks for the crosses. They researched that out.
"When we put the crosses out, I got the maths classes to work out exactly how the crosses should be sited. There's quite a science to it, you know. You can't just plonk them down.
"When it came to the service, we have air cadets and naval cadets at the school, they led the march all dressed in their uniforms. I got someone in the music department to play the Last Post.
"I got the head girl to give an address from the school kids' point of view.
"Ran competitions for poems. The best poems in English, Māori and French were read out at the service."
A woman read about the school's plans in the Bay of Plenty Times and got in touch with Armstrong, saying her uncle, who had lived in Gate Pā, had fought in the war after lying about his age. He didn't return.
This woman loaned some of her uncle's things to display at the school. She also accepted an invitation to speak at the school's service.
"She was great."
It's not easy marshalling all the different school departments - in a secondary school, you've got a lot of staff with their own workloads and special interests, but it all worked out and the service was memorable.
The staff at the college have a real camaraderie and its this that will be one of the hardest things for Armstrong to say goodbye to.
They had a special dinner for him last week at an Indian restaurant and farewelled him at a staffroom get together on Thursday.
"Everyone who retired says they will miss the students. And that's true. But I'll also miss the camaraderie of the staff.
"There's a lot of that in teaching. In the breaks, we descend into the staffroom and there's always a buzz.
"It's a very special staff. They are just a good group of people."
And they think that of him too.
The latest school newsletter contains a farewell message: "Mr Armstrong will be remembered for his quick wit, incredible knowledge, great costumes and commitment to Tauranga Girls' College."
Former principal Pauline Cowens, who retired last year, was one of a slew of people he's worked with or taught over the years sending him their wishes.
He shows photocopies of some of the messages - one from a Supreme Court justice and the other from a professor who's assistant vice-chancellor at a university.
The professor says his training helps her to this day.
"Not a single day passes when I don't draw on this somehow, in some form," she wrote.
Armstrong is packing up his office, sorting through decades of teaching material and memorabilia.
Picking what to get rid of is hard - what if it might come in handy in the future? - but he'll leave knowing he's a had a real impact on thousands of lives.
What's his fondest memory of being a teacher?
"Well, the last day of school is always fun," he quips, cracking up.
"That's a hard question. A lot of teachers will say it, and I'm going to say it too.
"It's a student who hasn't clicked on something, then BANG, they click. That's a neat thing.
"It's great to do the softball challenges, the overseas trips, they were great memories.
"But on an everyday level, it's those little things.
"That's what we do."
