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Revising my Views on the Impact of Teachers

In No One is Even Trying, I wrote that Grant Sanderson’s Youtube channel 3B1B has 161 million views. Based on how Youtube counts “views”, that’s between 1.3 and 21.4 million hours of learning.

This is incredible to me. If you asked me last night who my hero is, I would have said Grant Sanderson. If you asked me what’s wrong with the world, I would have said that there aren’t more people like him.

But maybe there are.

A regular teacher, teaching 8am–3pm 180 days a year to a class of 20 is producing 25,000 learning hours a year! Over a 50 year career, that’s 1.3 million, same as Sanderson, though in 10x as much time.

It’s even more surprising to compare a teacher with Khan Academy. Depending on how you count “views” they’re at 15 million to 120 million learning hours. But they have 600 employees, and they’ve been around for 12 years. So that’s best case 17,000, worst case 2,000 learning hours per employee per year, compared to a regular teacher’s 25,000.

That’s a little unfair, Khan Academy hasn’t had 600 employees for the full 12 years. But if we assume linear growth, they’ve averaged 300 employees, which would increase their learning hours to 4,000 (best case 33,000).

To be clear, the point is not that Khan Academy is bad (they have way more than lectures, and they’re available to anyone with an internet connection for free). The point is that seemingly non-scalable things like teaching can still multiply out to surprisingly large impact.

Since views counts on Youtube are legible and quantified, it’s really easy to see 100,000,000 and feel really impressed. But counting a view as 30 seconds, a teacher with 20 students and a 50 year career could hit 1.3 million learning hours, the equivalent of 151 million “views”!

Until now, I didn’t have that much respect for teachers. I understood that they’re probably good people, and a lot of them teach as a labor of love, but I didn’t appreciate their impact.

In fact, teaching has been my go-to example for illustrating how effective altruism differs from lay person opinions. Teaching seems like a great job, but if you think about it through an EA lens, it’s just not very impactful. 80,000 hours has very negative reviews of teaching, and another article of reasons not to go into education.

Nothing I’ve learned recently invalidates those articles. And yet, it’s hard to reconcile my belief in the seeming inefficacy of teaching jobs with my reverence for Sanderson. As always, one man’s modus ponens is another man’s modus tollens. I can have whichever belief I want, but not both of them at once. Either teachers are heroes, or Sanderson is merely moderately praiseworthy.

To further drive this point, consider the scenario:

You’re driving through a small town, and while stopping for lunch, hear rumors of a teacher who delivers unusually engaging lectures. As someone interested in pedagogy and social impact at scale, you decide to go check it out in person, and sure enough, the teacher’s amazing!

What would your first thought be? If you’re like me, your first conscious reaction would be “we’ve got to get this guy on Youtube!” If you’re like me, you see it as a horrendous waste of potential that this brilliant educator is stuck in a small town when he could be on the internet, delivering content to the masses at scale.

So you talk to him, set up a small film crew, convince him to take time off teaching to record Youtube lectures, and sure enough it’s a hit! Within your first few years, he’s up to 10 million views.

And yet, it turns out that intuition is totally wrong. He was already clocking in “10 million views” every few years. Of course there are benefits of being online. The content is recorded, the students could be anywhere in the world, you can go back if you missed a section. But none of that feels sufficient to justify my initial reaction.

Maybe I’m just a shameless technophile retroactively justifying my beliefs, but I think there’s still a good reason to revere Sanderson.

I love 3B1B videos because they’re creative and engaging in a way that math never was in school. It genuinely feels like he’s broken through whatever obfuscation prevents kids from understanding math, and discovered better ways of explaining key concepts. And because math is so fundamental to reasoning, this is more than a good educational channel. It feels almost like a leap forward for civilization.

But still, that’s not a metric effective altruism cares about. Maybe the real modus tollens is to abbandon the value system.