I was talking with my brother about how terrible our elementary and middle schools were (although we were in G&T programs, they were in the ghetto and we were by far the brightest in our classes), and I thought about how bad the American educational system is in general. Two examples came to mind:
1. Economics. When subprime mortgages were starting to fail and it was starting to become a big thing, I had to do some research before I could understand why subprime mortages had been issued in the first place. I never had the option to take a class in economics before I got to college (at which point I did take a couple of courses), but I think it's probably one of the most important social forces on earth and I'm embarrassed by my limited knowledge of the subject.
2. Science. I'm essentially a solid state physicist, so maybe my point of view is biased, but I don't know any non-physicists who have even a basic understanding of the electronic structure of materials. I guess you need to know quantum mechanics to be able to calculate the bandstructure of a material, but even a 4th grader should be able to look at the band structure of a crystal and determine whether it's a metal, semiconductor, or insulator, and how those types of things should behave as a function of temperature or the curvature of the bands.
Neither of these subjects are easily picked up by reading about them (since book chapters can get technical really quickly and newspapers can be stupid when they discuss them -- my mom reads the newspaper every day and still thinks homeowners are the primary cause of the financial crisis), but does anyone else have anything they think we should all learn more about?