Albus Dumbledore was known as the greatest Headmaster Hogwarts ever had, and it had many.
Before he became the Headmaster, Dumbledore was a teacher at Hogwarts. From what we know, he taught Tom Riddle and Newt Scamander before him, but apparently, both of those wizards got different education from Albus Dumbledore.
What Did Dumbledore Teach in Harry Potter?
In the Harry Potter series, Albus Dumbledore taught Transfiguration before becoming the Headmaster.
The first mention of Dumbledore’s post at Hogwarts was in Chamber of Secrets. Without knowing Harry’s connection to Dumbledore or Hagrid, Tom Riddle told him about what happened during the last time the Chamber was opened.
Tom boasted about his brilliant plan to blame Hagrid, mentioning Dumbledore as his Transfiguration Professor, the only one who didn’t like him as other Professors did.
The second mention about Dumbledore’s teaching position at Hogwart came from the short life story J.K. Rowling wrote about Minerva McGonagall. In that story, Minerva got a teaching post under the Head of the Transfiguration Department – Albus Dumbledore.
There is no mention of whether Dumbledore was a teacher himself, but from his job as a Head of Department, we can assume that he taught the subject himself.
What Did Dumbledore Teach in Fantastic Beasts?
Albus Dumbledore taught Defense Against the Dark Arts in the Fantastic Beasts movie.
There was some controversy about Dumbledore’s teaching post in the Fantastic Beasts franchise. It didn’t align with the official Harry Potter canon, and fans went into a spin. Nobody knows if this was made purposely or just a small mistake. However, it inspired a lot of fan theories that try and explain Dumbledore’s career change.
From the Harry Potter books, we know that Dumbledore was teaching Transfiguration in 1943, and more than likely beforehand, as Tom Riddle never mentioned Dumbledore being a new teacher.
Also, at the time, the Defence Against the Dark Arts Professor was Galatea Merrythought, who Dumbledore said was working at Hogwarts for nearly 50 years. We have a good source telling us that Professor Merrythought retired in 1945, which meant she was a teacher at Hogwarts since the late 1890s or early 1900s.
One of the theories says Dumbledore and Merrythought swapped their subjects throughout the years of teaching, claiming that Dumbledore started his career as a Defense Against the Dark Arts Professor and then transferred over to teach Transfiguration.
How Long Did Dumbledore Teach at Hogwarts?
Dumbledore has been teaching since at least the 1910s until he became Headmaster. The exact year when Dumbledore became Headmaster at Hogwarts is a mystery, but we can guess the timeframe.
We know that Voldemort graduated in 1945, and he worked at Borgin and Burkes straight after school for a few years. He killed Hepzibah Smith at the end of his shop assistant career and fled.
He came back ten years later to Hogwarts to ask for a teaching position. At that time, Dumbledore became a new Headmaster. If we assume that Voldemort was working at the shop for at least two years, we can accept that Dumbledore became Headmaster sometime after 1947.
Another clue on the date of Dumbledore’s appointment for Headmaster is the story of Remus Lupin. He was born in 1960 and bitten by a werewolf in 1964.
From what he told Harry, Lupin thought he would not attend Hogwarts because of his condition, but then Dumbledore became Headmaster, and Lupin was allowed to study. It indicates that Dumbledore became Headmaster no earlier than 1964 and no later than 1970 when Lupin went to Hogwarts.
It means that Dumbledore was teaching at Hogwarts for at least 64 years before becoming Headmaster.
Was Dumbledore a Good Teacher?
Dumbledore hoped that he was a good teacher, and from Harry’s reply to the hope, we can guess that he succeeded.
“I had proven, as a very young man, that power was my weakness and temptation. I was safer at Hogwarts. I think I was a good teacher.”
“You were the best.”
That could not be the most objective opinion, but from our knowledge of Dumbledore and how he treated his students, and how loyal they were towards him, we can gather that he was a good and respectable teacher.
Dumbledore didn’t judge anyone until he knew them well, and even then, he tried to understand the situation.
Dumbledore very rarely got angry with his students, if at all. From the way he treated Tom Riddle, we can say that he believed in second chances and that everyone had some good in them. Dumbledore also understood his students. All those traits make Dumbledore a good teacher.
Dumbledore’s career as a teacher, whether Transfiguration or Defence Against the Dark Arts, was long, and we hope for his sake a fulfilling one. Despite his many secrets and sad past, he taught us about many aspects of magic and equally many non-magical aspects of life, like love and respect for others.
Even after becoming Headmaster, Dumbledore never stopped teaching. It didn’t make a difference to him whether he was addressing students or grown people, he always had a lesson to teach.