Lots of reasons. To start with it is positive for the bottom 5%. School is also not just about academic results but also integration and socialization. I think that ideally you would have one class and several teachers.

If integration and socialization is important, perhaps we should outlaw private schools and redistribute all students across nearby schools randomly, so the rich kids get to understand what it means to be poor from the early age.

Dragging down the top 5% to the lowest common denominator is not a benefit to society overall. Would you recommend cancelling AP classes?

This is a big subject; none of us are in a position to do anything other than philosophize. But I do think that when your goal is "socialization" you don't need to force everyone to study the same thing. I think it's a moral tragedy that we hold back our brightest students.

Could you perhaps tell me what AP means? Thanks!

I’m guessing he means “Advanced Placement” here.

Sorry should not have used an abbreviation: "Advanced Placement" -- courses meant for excelling students.

> courses meant for excelling students

I took a couple of them and dropped them as fast as I could. I found the classes mostly just included more homework than was necessary. I thought it’d be more like university and focus more on lecture, notes, and reading. Writing more essays and more projects was a big NOPE for me.

How do you identify the students which belong in the separate classes, and at what age do you do it?

It's not uncommon for students to switch between top 5% and bottom 5% - yet people act as if its static. Education and chid development are ridiculously complex. It's not possible to have a solution that solves for everyone.

That's a good question that has several reasonable answers (also depending on context), so we should run some proper experiments to find which answers are best.

Though from a policy point of view, we don't need to know those answers: different schools should try different answers (including sending all kids to the same class), parents should send their kids to the schools they deem the best overall package.

As long as you permit or even enforce periodic rotation between the "tracks" when appropriate given the performance/speed of learning, you might as well start early.