Becoming a master teacher

How assessing learners helps teachers grow

One of the criticisms of a mastery-based learning approach is that it relies too heavily on assessments.

Doing assessment well is not a trivial thing. But it can be done well. And it is worth doing well for many reasons.

Assessing a learner's skills well is good for them. And that will be the subject of another article.

This article is about why assessing a learner well is good for a teacher.

A good assessment...

This article focuses on one specific use case of assessments, one thing that assessments can do: assessments inform a teacher about the skills of a learner.

This might seem like a pretty obvious use of assessments in education. But there are other uses, so it pays to be explicit about things.

By this limited definition, good assessment answers specific questions about a learner. It should have a good signal-to-noise ratio.

If a learner does poorly on an assessment, it should not be because they were tricked by a tricksy question or led astray by a wall of text. It should be because they did not grasp the skills under assessment. (If the skill is to be immune to trick questions and text-walls, then go right ahead.)

If a learner passes an assessment, it should not be because they successfully crammed a bunch of transient knowledge into their heads or memorized a bunch of unconnected facts and textbook definitions. It should be because they have actual knowledge and skills.

A good assessment gives the teacher a glimpse into the learner's mind.

What have they grasped? Where are they falling short? What are they misunderstanding? Where did that misunderstanding come from?

Illusions of competence

Teachers are not immune to cognitive biases; they can think they are good when they are not. Dunning-Kruger walks with all of us.

If you teach a thing badly and then assess it well, you'll know where you fell short. You might think you explained something elegantly, that the learners were following along, and that you dropped some serious pennies.

And then, when faced with the result of an assessment, you could conclude that very little value was added by your efforts.

Assessment is feedback to the teacher about the effectiveness of their teaching.

Of course, the signal-to-noise ratio of this feedback isn't great by default. For example, learners who are distracted could do badly, even on a well-designed assessment.

But there is signal. And it is worth paying attention to.

MBL feedback

Imagine learning to play tennis by hitting a ball off the edge of a cliff. Compare that to playing against something that hits back.

Learning to teach by making damn sure that every learner gets it at every step of the way is like hitting a ball to the learners and letting them hit it back. You know if your lessons land because you need to deal with the consequences if they don't.

A piece of advice I often give students is: Find a way to test yourself. Give yourself the opportunity to be wrong. That will tell you where your skill gaps are and how to direct your efforts.

This advice holds true for teachers.

Don't just assume you are teaching well, check your work. Check it often and check it well.


Lecturing a big class and moving forward, whether people are ready or not, is like hitting a ball into the void and not even watching where the ball goes.

It's not impossible to have a good lecturer, there are many, but the mechanism itself is optimized away from the teacher's growth. And also the learners', but that's for another story.

And it's not like lecturers get no feedback at all. The feedback is just slow, noisy, and has a low resolution compared to MBL-style courses.

With cohort-paced, one-to-many teaching systems, it's easy to be sloppy, to encourage illusions of competence in learners, to cut corners, and to pat yourself on the back and tell yourself you are doing a good job when you haven't confronted the quality of your results.

But what if the problem is the students

What happens if you are doing your dambdest to teach some learners a thing and they just are not getting it? It might not be you, it could be them that's the problem.

There is a limit to what a teacher can do. The best teachers in the world cant get literal potatoes to grasp simple arithmetic. There are some cases where teaching can be futile.


It's important to realise that there are a few moving parts involved in helping a learner get to mastery. The learner is a part of the system and so is the teacher. The teacher's job is not simply to tell the learner about the subject matter, do an information dump, tell them to study, and expect great things.

A good teacher is not someone who simply has a good grasp of the subject matter.

A good teacher should aim to make good students. There is a science to learning. There is an art and a science to teaching.

MBL is hard!

I talk about Mastery-Based learning a lot. MBL is hard to implement, and it's expensive.

You start off with a bunch of noob teachers trying to learn how to assess things properly and students finding new ways to cheat the system and optimizing for the wrong things.

Eventually, you can get good at assessing, but it's still operationally challenging - learners in an MBL course are all in different places; they need to be tracked as individuals. Teachers need to know who needs help and they need to spend the time helping individuals move forward.

If there is even a small crack in the educational content shared with the learners, then that can lead to repetitive interactions. So everything needs to be really well put together, crystal clear. But if you make things too clear - too easy and spoonfeedy - that causes other problems.

MBL is hard to pull off. For many, it might seem impossible.

What's a lecturer to do?

There are a few lessons an educator in a more traditional classroom/lecture-based system can apply:

  • incorporate frequent low-stakes testing into teaching and pay attention to the results
  • explicitly give more attention to the weaker and slower learners. They will tell you where things are falling short
  • interleave optional "advanced" material into a course so that faster students have something to do while you try to help the weaker/slower learners
  • try to understand the learners individually. Try hard. Think of their minds and their misunderstandings as puzzles to be solved. Be curious
  • explicitly hone your teaching skills outside the classroom. There are many fantastic books about teaching. I highly recommend Make it Stick; it's brilliant. And tell your 'earners to read it too

The most important thing to know is that teaching is not a you-either-have-it-or-you-don't attribute. It is a set of skills that can be honed.

If you want to hone your skills in a way that is efficient, you'll want to know where your skill gaps are. This is true for anyone learning a skill. Teaching is a skill.

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