What might surprise us though, is just how dramatic the difference between an effective and an ineffective teacher can be.

In some studies, students taught by the most effective teachers can make two years’ worth of academic progress in a single year, while those with ineffective teachers may learn less than half of what they should.

That’s a staggering 18-month gap – in just one year. Now imagine that child experiencing two consecutive years of ineffective teaching. The learning loss is not just cumulative – it’s compounding.

Students fall further behind, and many never recover. This is not a theoretical problem, it is a known one. And it’s exactly why school leadership cannot afford to be passive in their role of leading their school.

This is also why consistency is not just a nice-to-have – it’s a non-negotiable.

The Inconvenient Truth About Variation in Teaching

We often pretend, institutionally and professionally, that all teachers are equally competent – but we know this isn’t true. Parents know, students know and teachers themselves know.

And yet in education, we resist saying it out loud, and, in many cases, resist doing anything about it.

Other professions have clear, external mechanisms for ensuring standards of practice – think doctors, lawyers and accountants.

In education, teacher competence is largely self-regulated, assessed (in theory) by standards that are rarely tested or enforced in practice.

And herein lies the conundrum: principals know who their best and weakest teachers are, but most systems give them limited leverage to act on that knowledge.

Unless a teacher is grossly underperforming – below even the lowest threshold of acceptability – it’s near impossible to initiate meaningful change, let alone exit someone from the system.

So, what can leaders actually do?

Leadership’s Leverage: Consistency, Clarity, and Collective Practice

If high-impact teaching is the engine of student learning, then leadership is the system that keeps it finely tuned.

Great teaching doesn’t happen by chance – it’s cultivated, supported and aligned by leaders who are relentlessly focused on instructional consistency, something I spoke to recently when addressing Independent school leaders in Hobart.

That means school leaders must build systems where:

  • Common instructional frameworks are agreed upon and enacted school-wide.
  • Language, cues and symbols of instruction are consistent from one classroom to the next.
  • Teachers are supported to refine their practice within a shared vision of what effective teaching looks like.
  • Outliers are brought in, not tolerated on the fringes – even when they’re “good in their own way” – because misalignment breaks the instructional chain

This is especially important in the case of the so-called “good teacher” who refuses to align. Their independent approach might yield short-term success in their own classroom, but it fractures the broader system.

When instructional language, routines, and methods shift dramatically year to year, students spend weeks – sometimes months – reacclimating.

The next teacher is forced to repair that instructional discontinuity before they can move forward.

The cost is subtle but significant – a quiet erosion of progress that accumulates over time, something I have seen first hand in schools that I have led and sat idle until it was almost too late.

To prevent this, leaders need more than vision – they need levers that turn shared beliefs into shared practice (as outlined in the graphic I have created below). 

That’s where coaching and instructional rounds come in. Instructional coaching provides a structure for meaningful, one-on-one feedback that, in the case of Dayton, is grounded in our instructional playbook and learning area handbooks.

It helps teachers sharpen their craft within the shared framework, not outside of it.

It’s developmental, not evaluative – and it plays a critical role in building teacher efficacy and reinforcing the language and routines we expect to see across every classroom.

Instructional rounds give leaders a lens into school-wide practice. They allow patterns to emerge: where alignment is strong, where clarity is missing, where expectations need to be retaught or reinforced.

Rounds aren’t about judgment – they’re about feedback on the system itself. Are we seeing what we said we’d see? Are we delivering the kind of consistent, high-quality learning experiences that our frameworks promise?

These practices don’t just support individual teachers – they strengthen the entire ecosystem. They ensure that what happens in one classroom connects to what happens in the next.

That every teacher contributes to, and benefits from, a shared professional culture.

And that every child moves through school with fewer disruptions to how they learn and more momentum in what they learn.

Teaching Is Teamwork: The Pit Crew Analogy

Atul Gawande’s comparison of high-functioning teams to a Formula One pit crew is apt for schools. Everyone must know their role. Everyone must execute with precision. And everyone must work from the same playbook.

There is no room for freelancing in the middle of a high-stakes race. The same is true in schools.

In high-performing schools, teaching is not an individual sport – it’s a team pursuit. Great schools don’t rely on a few heroic teachers.

They build collective efficacy, where every student benefits from strong, aligned teaching year after year. That takes deliberate, active leadership – and it also takes tools that make that kind of cohesion possible.

That’s exactly why, at Dayton, we’ve developed an instructional playbook – to ensure every teacher is on the same page about what high-quality instruction looks like in our school.

The playbook defines the “what” and the “how” of our instructional ecosystem.

It’s not just about standardising practice for the sake of it; it’s about providing clarity, direction and shared language, so that instruction is not left to chance or individual preference.

When every teacher draws from the same core approaches, students benefit from predictable, high-quality learning experiences – no matter whose room they’re in.

This is further strengthened by our learning area handbooks at Dayton, which provide the specific application of our instructional framework in subject domains (particularly English at this time, with more to come in Maths soon).

Together, these documents are more than reference tools – they are anchors for professional dialogue, instructional decision-making, and collaborative planning.

They ensure that our instructional culture is not built on memory or personality, but on shared purpose and evidence-based practice. 

The Leadership Imperative

This is why leadership matters! Not the title, not the administration, but instructional leadership – the kind that ensures coherence, builds capacity, and refuses to let variation go unchallenged.

Leadership that actively defines what good teaching looks like in this school, and creates the conditions for every teacher to teach well – every day, for every child.

Without that, schools become a lottery. A child’s success hinges on which classroom door they walk through each year. And that is a risk no school should be willing to take and it is certainly not a risk we are willing to take at Dayton.

So, yes – it matters what teachers do in their classrooms.

But it matters even more what school leaders do to make sure every teacher delivers.