I hope the class was conducted under a spreading chestnut tree.
Indeed. The point of learning to diagram sentences isn’t that sometime in your life you’ll have to diagram a sentence. What I learned from diagramming sentences wasn’t how to diagram sentences but how sentences work. And that’s something I’ve used a lot, maybe whenever I read or write, and certainly when I get into discussions about grammar or syntax in places like the SDMB.
And something similar could be said about a lot of “useless” skills.
Fractions absolutely do come up in “real life.” There’s not a clear line between knowing how to do “arithmetic appled to fractions” and understanding the basics of what fractions are and how they work, which is necessary for such mundane questions as “How many votes needed for a two-thirds majority?” or “Which hamburger is bigger (and by how much), a quarter pounder or a 1/3-pounder?”
Not to mention, someone who can’t work with fractions is going to be at a serious disadvantage if and when they study more advanced math, like algebra or probability and statistics.
Right, I don’t know how you can get through modern life without understanding fractions (or related, percentages for that matter).
Anecdote: there’s a (maybe apocryphal) story about a German footballer (soccer) from the 60s who was negotiating a new contract with his club’s management. They offered him a one third salary raise, and he indignantly answered “I want at least a quarter!”
Any of us who took Latin, for starters.
I definitely don’t count Latin in the useless category. Like others, it taught me a lot about how linguistics works in general, and it also helps a lot with other Romance languages. Like, I don’t know Spanish, but on multiple occasions I’ve been able to communicate meaningfully (if crudely) with monolingual Spanish speakers, due in part to my Latin knowledge.
OK, maybe it would have been more useful to learn Spanish. But Latin was a lot of fun.
I honestly can’t think of a single skill I was taught that I would consider “useless”. I was born too late for slide rules in school, but my father was an engineer and insisted on teaching me to use one. Yes, it was already obsolete, but it taught me how to visualize mathematics, which made learning math easier. Studying Latin in the 7th grade opened the door to language learning for me. In my senior year of high school I was taking Latin IV, AP Spanish, and AP German simultaneously and they were the only subjects I did well in*. After high school I enlisted in the Navy and graduated with high honors from the Basic and intermediate Russian programs at the Defense Language Institute. Even learning to square dance in junior high school gave me a sense of timing, coordination and balance that proved useful in developing skills I care about like music and sailing.
“Obsolete” is not the same as “useless”.
ETA: * - I could have done well in other subjects if I had been as interested. I simply didn’t put in the effort.
More useless knowledge than skills. Why was it important to drill into us the difference between Corinthian, Ionic, and Doric columns?
So that your McMansion doesn’t look anachronistic?
How else are you to advance through the ranks of Freemasonry?
More seriously, a basic education should contain a wide range of subjects. It gives people a chance to find their own niche. You weren’t interested in the columns, but perhaps for one of your classmates it was the first step towards a successful career as an architect.
Differential equations. I was was more than good at them, top of my class. Often was asked to present my solutions on the board.
When I took Dynamics class the teacher assigned us a problem that required using Differential equations and I was the only one to solve it and presented it to the class, I was so proud. Then the instructor told us that we would not be using them any further in the class and the the new, simpler method was vector analysis. The class cheered, I was disappointed.
Not once in my 45 year engineering career was I required to use them to solve a problem. Not once.
I’m having a hard time imagining any problem that could be solved both with differential equations and with (non-diffEq) vector analysis… Unless you were going WAY too back-to-basics with Newton’s Laws or something?
I once learned how to determine iambic pentameter in a poem. Don’t believe I’ve had the opportunity to use that skill since high school English class.
Without knowing cursive, kids would grow up not knowing how to sign their own name!
Already well addressed by @DPRK
Even if you never in your life had to write a traditional line of code, understanding the fundamental logic of programming is part of a well-rounded education and undoubtedly extends into many other areas of modern technological life. I was about 10 or 11 when I first learned FORTRAN, and it really opened my eyes about how computers really worked. Until then they were just mysterious black boxes that understood some sort of “language” that I imagined to be something like English. I later figured out that, on the IBM 7040/7044 series, you could get an assembler listing along with your source code, which was even more revelatory because it showed me the association between FORTRAN statements and machine code.
So you young whippersnappers never learned octal? Back in my day (said the old geezer) octal was the most common representation because it was well suited to machines common at the time whose word length was a multiple of three bits – 12-bit, 18-bit, and 36-bit. Hex became dominant with the introduction of IBM’s System/360 series, with its 32-bit word and 8-bit byte addressing. Even then, DEC stuck with traditional octal for the 16-bit byte-addressable PDP-11.
Yes, we also learned octal, but I never used it in any software project I’ve ever done. Because I’m a young whippersnapper (almost hitting 60 
)
Personally, I think that lawyers should be required to take at least one programming class, just because it’s such a great example of clear, unambiguous language. Granted, the law covers a much broader subject area, so that level of clarity is much harder and sometimes impossible, but it’s still a goal to aim for.
Why can’t they just print their name? There is nothing special about cursive. So many signatures are barely legible anyways.
Which is worthless. I was shocked to discover this some decades ago in my thirties when I was hanging with a couple of friends in their twenties. They had never learned to write cursive and when I asked how they signed their name, they just showed me the stylized scrawls (“faux cursive” I suppose) they had come up with and maintained consistently. It was my first real introduction to obsolete life skills.
Just as I suspected – a youngster! I bet you probably never had to enter the code for the basic paper tape loader on a PDP-8 through the console switches! The code was written out (in octal) on a bit of paper that was traditionally taped to the front of the machine. The console switches were arranged in groups of three, distinguished by colour. The switch positions for any octal digit are permanently etched into my ancient brain! 
Here’s an example of something that wasn’t as useless as it might have seemed at the time:
I was in elementary school when they were teaching New Math (parodied so well by Tom Lehrer). The idea was that it was important to teach underlying concepts, not just the mechanics of doing arithmetic. One of the concepts was the representation of numbers in bases. They had us doing arithmetic in base 5, and converting numbers back and forth between base 5 and base 10.
It was a lot of busy work, and no one uses base 5 for anything as far as I know. But the concepts I learned became very useful when I started learning about computers and how numbers are represented in base 2, base 8, and base 16.
If I were to go back and redesign the curriculum, I’d have it concentrate on the bases that are used in computers, and I wouldn’t have students spend so much time on arithmetic in different bases. Overall, though, learning about representations of numbers in different bases was a good thing.
The computers I learned to program first were the C64 (at home, in Basic) and Apple IIe (at school, in Pascal), and gladly they already were 8 bit and had keyboards.
When I was studying Russian some of the students were complaining about the number of cases. IIRC, there are five in Russian. The teacher said be glad it’s not Polish – it has 13 cases!