I visited the USAFA in 1972. I shared a room with one of OCdts in his last year, as he was preparing for his final academic exams for his degree. He was a couple of years older than me, but was struggling with some basic calculus. I helped him through some of the problems, but he was more astonished that I had done calculus in high school in the UK some two years previously. Lovely guy, and he gave me his squadron jacket. I still have it, though it has shrunk over the years - probably a manufacturing fault.