Some of the many schools of thought:
As a technician, you're there to "do" not to decide. So when you're given instruction, even poor instruction, your job is to just make them happy. In the professional world (and I don't mean just in theater, I mean everywhere) there are people who are pedantic, obnoxious, mean, Napoleonic jerks who like to
throw their weight around.
If this person isn't your supervisor but has some authority, you should be discussing this calmly, politely, and privately with the person who is. There's a chain of command for a reason. It should be followed.
If this person has no authority, you need to respond properly. What that response is depends on who the person is. Since they're a teacher and you're probably a student, you still need to respect their position, even if they are behaving poorly. But I suggest again, calmly, politely, and privately, take it to the supervisor.
Two cliches that are usually true:
The world is filled with two types of people, those who manage what they don't understand and those who understand but aren't allowed to manage.
Never let anyone else take control of your emotions.
And if all else fails, we could dig a hole in the desert.