So about 20-30 minutes into my warmups ... basically half note argeggios , I move from playing in the middle of the staff down to lower register to arpeggios that move up in half steps. I am trying to play at pianissimo. When I get to the A above the staff the pitch is flat, no surprise there, and pretty much any note higher than that. So I have the option of giving it a little more air to bring the pitch up or sort of pinching it to bend it up so I can keep the volume down. Also, the resonance is pretty much locked in on the lower pitches and relatively effortless ... but when I start getting up there I think I get a little active in the process. The increase air does bring out the resonance as well. I know I have to play the notes...well to be able to play the notes... sort of getting reacquainted with the upper register and it is a warmup, I don't feel tight or strained afterwards. How do you or how would you have your students approach something like this?