Basic personal finance would have been good to know about, but the school was good on critical thinking exercises - What is the truth? How to tell it from something that looks plausible but is full of bias and misinformation. What is YOUR truth? Why is it sometimes different from other people's? Sometimes difficult to grasp when you're a teenager, but so useful later.
Can problem solving be taught? How to take what looks like a mess or just too big to cope with and split it down into smaller, more easily solvable problems. The cleverest people I know in any field can do that easily and seemingly innately.
I think most of these things are learned through experience, though. I can't conceptualize a curriculum in school that could effectively teach a bunch of kids and teenagers how to, say, apply critical thinking. Absorbing knowledge into your day to day thinking patterns, and simply "learning" and being able to recall facts in a test, are two different things, and the latter is the default mode of acquisition in school.
I think school is just not that good of a setting to learn these things.
I mean, you got 20-40 young people in a room, most of who are just sitting here because they have to, trying to pay attention while their mind wanders elsewhere, and here you are as an adult trying to make them absorb entire thinking patterns into their day to day consciousness? Nah... Those things develop through experience: you can't teach me critical thinking by telling me about critical thinking, but
making the experience of seeing yourself, or a thing you like, being misrepresented somewhere, can teach it to you very quickly.
I remember reading about a lovely park near my house in the newspaper, with people calling it a "crime, violence and drug hotspot", and almost falling over in my chair! It was anything but, it was actually a very nice place, only that there are a lot of immigrant-looking people there. They're just chilling there with their families talking and having fun, but for some reason the newspaper made it out to be a crime hotspot completely unjustly, probably due to racial prejudice. And once I understood that, I definitely don't trust most things people write about "problem areas" anymore until I have been there. Or take my degree; ever since I know a lot about linguistics, I see SO MUCH bad linguistics everywhere even in huge media, popular science and official communications that I just can't trust anything in areas I
don't know about.
Some school settings and societies might alleviate these issues though simply by giving more opportunities to gain life experience during the formative years.
In East Germany for example, they had "polytechnical" schools. It was a unified ten-year school system where you:
(1) remained in the same class from elementary school ages all the way to graduation
(2) had a lot of classes about practical life and work-related skills, including the nominal polytechnical classes
(3) had one day a week of working an internship-like job in actual production, giving you plenty of opportunity to become independent and self-sufficient and become connected mentally to the real world, the worth of things, the experience of taking responsibility, social skills and much more
(4) learned your own regional dialect in addition to standard dialect, supporting regional minorities and endangered languages
Just look at these subjects: German, another foreign language, informatics/programming, maths, physics, chemistry, biology, arts and crafts/carpentry, economics, geography, astronomy, gardening, technical drawing, sewing, "Staatsbürgerkunde" (mostly how to do your papers, how to live properly, how to do taxes and so on), art, music... Plenty of things you don't get these days! Gardening?? Sewing?? Economics?? Crafting??
Everyone I know who grew up there had remarkable life skills at a very young age and was very happy with how they grew up in that respect, excepting of course personal problems with teachers, coworkers or classmates. All of this combined with lots of nature and handiwork related activities in the universal teen scouts made them into pretty well rounded people. I know none of them who can't repair a bike by themselves these days - I can't because nobody taught me to be good with my hands (even though I would have liked to). :(