There is a quiet assumption underneath most of the English-teaching market, and it is worth saying out loud so we can examine it: that if someone speaks English well — better still, if they were born speaking it — they can teach it. Parents feel it, schools advertise on it, and it is almost entirely wrong.
Speaking a language and teaching a language are two completely different skills. Most native speakers cannot tell you why we say "a big red car" and never "a red big car," even though they would never get the order wrong themselves. They know the what without the why, and teaching lives entirely in the why. A person who has never had to consciously learn English has, in a real sense, the least direct insight into what it is like to struggle with it. Fluency is not a qualification. It is not even evidence of one.
So what actually makes a good teacher? Not a passport, and not, on its own, a diploma in the subject. What makes a good teacher is training — the deliberate, ongoing development of the craft of teaching itself. It is the single most underrated thing a language school can invest in, precisely because, like good curriculum design, it is invisible to the person buying the lessons. This article is about why it matters more than almost anything else in the building.
The teacher is the biggest variable — so the teacher is where training pays off most
If you read the research on language outcomes, one finding keeps surfacing above the others: the teacher is the single largest factor in how much a student actually learns. Not the textbook, not the classroom, not the app — the human being at the front of the room. Rigorous reviews of the evidence, such as the UK Education Endowment Foundation's work on language learning, keep landing on the same place: teacher quality dominates.
This should change how you think about spending. If the teacher is the biggest lever, then improving teachers is the highest-return activity a school can do — and the mechanism for improving teachers is training. A school that spends on marble reception desks but not on developing its teachers has, whether it knows it or not, spent its money on the small lever and starved the big one.
What "training" actually means (it is not a certificate you get once)
When we say training, we do not mean a laminated certificate earned in a two-week course five years ago and never touched since. That is credentialism, and it is nearly worthless on its own. Real teacher training is a continuous practice, and it has several parts:
- Pedagogical grounding — teachers understand why a method works, not just how to run it. A teacher who knows the reasoning behind eliciting language from students rather than lecturing at them can adapt it to a room that isn't responding; a teacher who only memorised the steps cannot. (We wrote about the underlying science in What Is Pedagogical Theory.)
- Observation and feedback — someone experienced watches real lessons and gives specific, honest notes afterwards. This is how every serious craft improves, from surgery to music, and it is astonishing how many schools never do it at all.
- Subject knowledge, deepened — not just "knowing English," but understanding its structure well enough to explain why, to anticipate the exact points a Mandarin-speaking learner will trip on, and to answer the hard question instead of deflecting it.
- Calibration across the team — training is also how a school makes sure that the lesson you get on Tuesday from one teacher and the lesson you get on Thursday from another are built to the same standard, toward the same goal. Without it, a "school" is just a collection of freelancers who happen to share a hallway.
Notice that none of this happens once. It happens weekly, in the ordinary rhythm of a school that takes teaching seriously.
Why so few schools do it — and what it quietly costs students
If training is so valuable, why is it so rare? The honest answer is uncomfortable, and it connects to something we have written about before: the babysitting trap (the full argument is in Why Linguists Are Almost Never Found in Language Schools).
Training requires two things most schools have already spent: management time and teacher stability. At a school built on underpaid, overworked, high-turnover teachers, management's hours are consumed by firefighting — covering no-shows, re-hiring, refereeing — and there is nothing left to develop anyone. And even if there were, why pour months of training into a teacher who will be gone by spring? So the school doesn't train, teachers don't improve, results stay mediocre, and the whole thing competes on price instead of quality. The student pays for this invisibly, in lessons that could have been far better and simply weren't.
This is the part worth sitting with: when a lesson is mediocre, the student almost never blames a lack of teacher training, because they cannot see it. They conclude that they are "bad at languages," or that English is just hard. Very often the truth is that no one ever developed the person teaching them.
How we do it the other way round
We treat training not as a box to tick but as one of the core reasons a school exists at all. It is deliberately wired into how we operate, and — as with everything we do — each piece depends on the others.
Because we pay and support our teachers properly, they stay, which means training compounds instead of evaporating — a teacher gets meaningfully better over years rather than being replaced every few months. Because pedagogy experts sit in the design and management of the school rather than being bolted on, the people giving feedback actually know what good teaching looks like and can say why. And because we track real learning data through our own ecosystem, feedback isn't guesswork — a teacher can be shown where their students consistently stall and given concrete tools to fix it.
That is the difference training makes, and it is why we think it is the most underrated line in the entire budget. The nationality of the teacher at the front of your child's classroom tells you almost nothing. What that teacher has been trained, supported, and given the time to become tells you almost everything.
Curious how a training-first school feels from the inside? Read our ethos, come and meet our teachers at an event, or browse our courses. We're always happy to explain the why.