I've found something to answer that question:
"They came as teenagers from every state in the Union, wearing every mode of dress from country homespun to tailored city surcoats. In their freshman were officially known as plebes (perhaps from plebeian, ‘a commoner’), though upperclassmen called them ‘things, ‘animals,’ ‘reptiles,’ and ‘beasts.’ Despite their differences, these young men were united by a shared distinction: each of them had passed stiff entrance requirements. Each had been appointed by a U.S. congressman, was no younger than 16 and no older than 21, measured at least five feet tall, had no deformities, and was fit for the rigors of military duty. Each one had demonstrated proficiency in fundamental arithmetic. And every one of them was single; even overtly having a girlfriend was grounds for dismissal.
They were the antebellum cadets of the United States Military Academy at West Point. And although these scrawny schoolboys could not foresee it, they would one day face each other in battle, leading rival American armies in a hard-fought civil war."
By the common law the age of majority is fixed at twenty-one years for both sexes, and, in the absence of any statute to the contrary, every person under that age, whether male or female, is an infant.
-- The American and English Encyclopedia of Law, Garland and McGeehee, 1900
Was there even a standard of education back then? In studying a local college here, students were often 16 or younger, the college had to form a lower college to get students up to speed for the actual college.
I dont think there was an equivalent of high school then at all, most communities built their own schools and hired their own teacher for probally a 6th to 8th grade education?
It struck me rather odd how rudimentary the education they came with was......…yet were expected to do college in Latin and Hebrew......