After high school, there are any number of specialized programs you can follow that have an obvious result: training as an electrician, construction worker, chef, mechanic, dental hygienist, and so on; law school, medical school, architecture school, teacher college, engineering, library studies, counselling psychology, and other dedicated fields of study at university; and many others.
But I don't think most people who get a high school diploma really know very well what they want to do after that. I certainly didn't. And it's just as well.
At the turn of the 1990s, I spent two years as student-elected representative to the Board of Governors of the University of British Columbia, which let me get to know some fairly high mucky-muck types in B.C., including judges, business tycoons, former politicians, honourees of the Order of Canada, and of course high-ranking academics. One of those was the President of UBC at the time, Dr. David Strangway.
In the early '70s, before becoming an academic administrator, he had been Chief of the Geophysics Branch for NASA during the Apollo missions—he was the guy in charge of the geophysical studies U.S. astronauts performed on the Moon, and the rocks they brought back. And Dr. Strangway told me something important, which I've remembered ever since and have repeated to many people over the past couple of decades.
That is, when he got his physics and biology degree in 1956 (a year before Sputnik), no one seriously thought we'd be going to the Moon. Certainly not within 15 years, or probably anytime within Strangway's career as a geophysicist. So, he said to me, when he was in school, he could not possibly have known what his job would be, because NASA, and the entire human space program, didn't exist yet.
In a much less grandiose and important fashion, my experience proved him right. Here I am writing for the Web (for free in this case), and that's also what I've been doing for a living, more or less, since around 1997. Yet when I got my university degree (in marine biology, by the way) in 1990, the Web hadn't been invented. I saw writing and editing in my future, sure, since it had been—and remains—one of my main hobbies, but how could I know I'd be a web guy when there was no Web?
The best education prepares you for careers and avocations that don't yet exist, and perhaps haven't been conceived by anyone. Because of Dr. Strangway's story, and my own, I've always told people, and advised my daughters, to study what they find interesting, whatever they feel compelled to work hard at. They may not end up in that field—I'm no marine biologist—but they might also be ready for something entirely new.
They might even be the ones to create those new things to start with.