In the early 80s our entire SAT prep session consisted of being told one high school morning: 1 - fill the bubble in completely with the right kind of pencil or the answer wouldn't be seen by the machine and 2 - the formula of "if you don't know the answer, if you can eliminate at least one option, it's worth guessing".

A lot cheaper and more time efficient than buying a book, much less taking a prep class. Perhaps those options didn't exist back then?