Okay this is making me crazy and I can't figure out what to type into the google-machine to find an explanation. I'm hoping some of you smarty-pantsers here can explain this. I play bass (duh). If I play an A on my bass or on a guitar or on my keyboard, it's the same note/pitch. My daughter (11) plays clarinet, my son (13) plays trumpet. If I ask them to play an A, the note that comes out is a G (in my universe). WTH??? Is their school teaching them wrong or are their instruments tuned in a world where A does not equal 440hz? I do know that A has not always been at 440 and it's been creeping up over the last couple centuries, are they maybe just tuned to a very old standard? I just asked my daughter "how do you tune a clarinet?" and she said "I have no idea."