We need to admit the obvious about school: A good portion of one’s K-12 education is not going to be applicable to later life. This is, however, exactly as intended. Because we want our students to have a broad-based background in a variety of subjects, public education is by design both expansive and cursory—a mile wide and an inch deep, in other words. Specialized knowledge is taught in higher education and trade or professional training when, drawing on the wider knowledge of the primary and secondary school years, students focus intensively on more narrow career-based learning.
However, it does not follow that all learning is useless because some may later turn out to be forgettable. In fact, there are three skills that definitely must be mastered before graduating from high school, and the list is neither long nor arcane.
Learn to write well. I cannot emphasize this enough. Many jobs now require advanced writing skills. Even if the entry-level position you start with does not, your chances for advancement will depend on your ability to compose coherent emails, letters, proposals, evaluations, explanations, or whatever the position demands. You will be judged throughout your life on how well you write, so make sure you learn how—now.
Learn to read well. Our increasingly complex world produces paperwork the way the Midwest produces grows corn. Both daily living and work now largely revolve around reading unfamiliar material and extracting pertinent details. Whether it is absorbing a training manual or deciphering a lease agreement, it is all about reading, reading, and more reading. Whether you plan to be a farmer or a pharmacist, you are going to read more than you can possibly imagine. While you have the luxury of being a full-time student, make sure you always have a stack of books at hand and dive in. It will pay rich dividends throughout your life
Learn to study. It might seem impossible to graduate from high school without learning good study skills, but it is, unfortunately, more than possible. Good study habits require the ability to devote sustained attention to material, reorganize the material into a form that helps to remember it, and recall the material upon demand. Everyone has to spend the time learning what works best for them, whether it is note cards, summarizing, setting up dual column notes, using memory tricks like mnemonics, or whatever does the job singly or in combination. When I was a high school teacher, it always pained me to see students under-perform on tests because they could not find a way to translate what they knew into concrete and retrievable information. I know they studied—they simply did not study well.
None of my suggestions are, of course, meant to downgrade the importance of learning a whole lot more during your thirteen or so years of public school; this is simply meant to give you some idea about what you absolutely, positively should have in your head the day they put the diploma in your hand. I am drawing on my experiences working in secondary education, post-secondary education, and business to offer my own perspectives—and I am more than happy to concede that others may have their own list of three skills that are equally important. I chose mine with the idea they will provide useful pathways to whatever other skills and knowledge a student may wish to pursue.
Also, before anyone assumes that I believe that some classes can be shirked, it would be best to remember that a great deal of subject matter is going to feed into the three basic goals I have outlined. You may not like tackling Lord of the Flies, but it will help you become both a better reader and writer if you engage with the book. Those complex chapters in your Chemistry textbook are a good exercise in learning to study and recall highly technical material.
Therefore, by all means, do learn both some Trigonometry and the tragic lessons of the Crimean War. You will be a more able person and citizen if you do. Just be sure you can write an intelligible essay on the war, read the chapter in the Trigonometry textbook, and study the material and pass a test on either. Your ability to manage both your life and career will be enhanced if you do.