Now back in ancient history when I was a freshman at MIT I had to take ROTC since it was required for all freshmen and sophomores. (This icon is a picture of me in my uniform). I think we had 2 hour classes a week were we were lectured on topics such as the theories of Carl von Clausewitz (1780-1831), lots of war history, how to take apart a M1 rifle and other such stuff. Sometimes they showed a movie and I think I had an early morning class (10am which was early for me) and it was always hard to not fall asleep when they dimmed the lights. And there was an hour of drill in the afternoon when we marched around on Briggs field or in the Armory with rifles and had to polish our shoes and brass buttons for the occasional inspection. We never got a chance to fire the M1s - alas.
In my sophomore year one of my friends got excused for flat feet. So I went to the MIT infirmary to give it a try. The doctor said "you don't have flat feet but what about your vision?" A quick trip to the eye doctor for an extra test and I got my equivalent of a IV-F. I turned in my uniform and was happy to no longer have to put up with this. Several years later it became no longer required and the officers who were the teachers were happy to no longer have to teach people who didn't care at all.
While at MIT and in grad school I had a II-S deferment and when I quit grad school and got a job as a computer programmer I was able to get a II-A deferment (critical industry).