Thanks Rotorhead, that's a start.
That's my problem, I searched for hours on the internet for an explanation but I couldn't find one. And as much as I could guess, I had nothing to confirm or deny my guesses.
The thing is when I was a student my CFI didn't have a clear understanding of this stuff so he didn't explain it to me very well, now that I have to teach it myself, I wanna try to give a better "service" to my students.