While I'm not a teacher nor experienced trainer, I advised my crew that the first step in learning to sail was to learn the vocabulary as it makes giving and receiving directions much easier and less confusing.
I don't really see the point in trying to force someone go learn all the vocab right up front. I've only been sailing for a couple of years and still don't know many of the correct terms, yet still manage to get the boat where I want to go. (I do know what the mainsheet is). Almost everyone I've sailed with to date has zero experience as well. When I want them to do something I just point at it and say "pull in that rope", "let out that line", ect... Terminology is irrelevant as long as they are doing the write action, as time goes on they will learn what your talking about. While they are performing the action you could then inform them what the name of the line is and next time they might have less of a dumb look on their face.
Another suggestion is get them to take a sailing course. They will learn a lot faster that way then being trained by you, for the simple reason that it removes the emotional asspect from the equation. Plus if they mess up something its not on your boat.
Sent from my GT-P6210 using Tapatalk 2