I would have to wrack my brain to think of anything anyone taught me in school that has ever been of any use to me in my adult life.
I knew how to read, write and spell before I went there. I suppose I got practice in it until the end of Grade 8. But since I was done with high school, I have never had to write a book report, fail to see the depth in a stereoscopic topographical map, watch condensation form on the outside of a can of ice, use algebra, sing sh***y music in a choir full of people whose voices are changing, try to paint a picture of anything, or much of anything else I ever did there.
School might be a worthwhile endeavor if they taught people how to cope with life after school is over, like how to pay bills on time, how to start accounts, how to rent an apartment or buy a house, how to save money, how to enter the working world, how to do things around the house to save you hundreds or thousands on repairmen... but they don't teach any of that stuff.
Mostly, I learned that it was deadly boring, and that an awful lot of people are complete a**holes.