The system you refer to is and in many regions had been phased out as it turns out that the splitting around 6th grade isn't really working well.

Also even before you had schools which covered multiple of this schools and allow students to "move" between them, sometimes in a per-course level.

There also always had been ways to get the same degree as from a gymnasium even if you initially ended up on a hauptshule, through it was a often shitty path and potentially took you a bit longer. While a few people which state out in a realschole doing it was the norm, for people on a hauptschule it was very very very unlikely.

Don't get me wrong the German school system is a mess, especially if composed to some of the Nordic states but it still beats the US.

The problem with that sort of tracking is that no one wants to be stuck teaching kids with "medium" and "low" skills. So these kids are going to get matched to the worst, lowest skilled teachers, and no chance of realistically getting back on the "high" track! You can of course fix that by rewarding the best teachers and training them better in effective instruction methods (i.e. nope, the kids aren't going to just "learn stuff on their own"!) but guess what, both of these are political anathema in the public schooling system. Especially in the U.S.

No. You can take a course to upgrade from middle to high tier after the fact. A friend of mine did the middle track first and after working a bit he then went on to university. He's now doing AI programming.

The system is quite fluid if you put in some effort.

Exactly. I would add that the spirit of system is realising that people have different abilities and training them accordingly to their potential, and there is nothing wrong with that. Realschule and Hauptschule are not there to try to get everyone back into gymnasium track. The merits of Realschule and Hauptschule are well established in society since they are the pipeline of people that end up in practical and technical jobs e.g. doing machine maintenance in factories and so on.

Some snark: it is mostly intelectuals that dread at the thought and possible implication that not all people are meant to get an university degree.To achieve that goal they are willing to degrade all standards so that anyone can have a pretty paper in wooden frame.

> they are the pipeline of people that end up in practical and technical jobs e.g. doing machine maintenance in factories and so on.

These jobs are going away in the near future. Nowadays the only people who work in factories are highly skilled engineers with complex e.g. CNC skills and a heavy math background.

How are you so sure about all that? I don't see which upcoming development would make machine setup, maintenance and repairs go away. It's exactly the stuff that computers are not good at. It's things that require high dexterity, improvisation, interaction with business functions etc - things that computers and robots are not good at.

I have a personal corollary to the Dunning-Kruger effect: If you don't understand why something is difficult, you are completely clueless about it. And most things are difficult in some way.

Chesterton’s fence as applied to Dunning-Kruger? I love it!

A CNC mill is a machine that needs to be maintained and operated by someone, and that someone is more likely to have learned the necessary practical skills in an apprenticeship and/or at a vocational school than at a university. You don't need a university degree to be a highly skilled worker, especially for jobs that require more practical experience than theoretical knowledge.

Oh my god!!! Sorry to react like this... Other people already commented that... That is sooooo much disconnected from reality it shows you never went to a factory floor. You never seen anything being produced in mass scale. Even the poster wall robot arms doing welding work need hundreds of people taking care of their set up, maintenance and much more. And those are complex machines. Even simpler machines such as steel presses that take in steel rolls and make steal parts of all shapes and sizes (e.g. car breaks, fridge doors, anything with steel actually) take a huge amount of set up work, management and maintenance. In Germany (which I know well) you see plenty of kids (18yos) in factories learning all these detaild skills from older workers. Takes them some years to become good and they are very sought after. Companies do worry if can get good high school kids to take their aprentiships. This has ZERO to do with higher math or bachelor's degree engeneiring education.

When I was In New York City public grade school (~1992/3) there was a similar system. It added the so called "top" classes for higher ability students and special education classes for lower ability students. These students were called "tops" and "speds" respectively with sped being a pejorative term. All that system did was pile every student with behavioral problems in special ed and all the kids who parents were on the school board in tops classes. Everyone else just went to class.

The system is less about ability than which social class one belongs to. Affluent -> Gymnasium Poor -> Hauptschule Realschule gets some of both

Is the stratification by social class an example of correlation or causation?

This could be rephrased as: Are poor people less able?

You seem to discount that as a possibility a priori. Why? There is a plausible connection between one's ability to thrive in a knowledge or skills-based economy and one's socioeconomic status.

I don't want to discount that as a possibility, it is much more a matter of fact. A lot has to do with wealthier people being able to afford better education and generally being able to invest more time in the offsprings chances on the jobmarket. This all leads to very able people having worse chances because they had bad luck in the socioeconomic class lottery when being born, thus unnecessarily restricting mobility between social classes.