What useful things are not taught as much as they should be?

Software Engineering.

As the tech progresses and individualism in software engineer rises, the 90s/00s software engineering pearls are forgotten by the new generation. Many of these methodologies were mistakenly buried in the criticism in mid 00s and removed from the course list. Some of my favorites and must-haves for an engineers are: - How to tell a user story (w/ storyboards, flowcharts, mockups, etc) - How to formalize your designed system (UML, hierarchy graph, sequence graph, etc.) without a tedious/ambiguous "design doc" - How to write documentation (target audience, minimal examples, etc.)

Economics and financial planning. Dont think any economic theory is perfect, but some help connect different systems in a framework where you can try to work out the motives behind things you read in the news.

The way I think about it is, there are certain areas of knowledge that divide the world into 2 kinds of people, where those that have that knowledge dominate and/or manipulate those that don't. That's how I rank what the most important knowledge is.

Law, economics/finance, mathematics - things like that spring to mind. In contrast, you're not in any danger of being financially ruined or locked up because someone else knew geology or English literature, and you didn't.

Outside of the USA in the English language communiry: rhetoric. If you wonder why you always seem to lose verbal argumentation, this and debating practice are probably why: it's not the actual merits of your case, it's how they are presented. In the U.S. and in some more exclusive schools both are taught.

Logic and philosophy would also apply

Domain specific instead of domain general.

What I mean, is that most branches of study require their own school the earlier the better.

Public school as a domain general educational process is a complete waste of time, money, yields absolutely nothing at all.