We always provide the big instruments but when it comes to the other instruments we ask parents to purchase instruments. When it comes to students using school owned instruments that are normally purchased I tell students that they are on a first come first serve basis and if I run out of school instruments you might have to play an instrument that is not your first choice. I never ask parents to verify why they need a school instrument. My theory is I don't want to lose any student that is interested in band. So if providing an instrument will allow the student to be in band I will make it happen. I have several students that wanted to play Alto on tenor sax instead because that is what is available and they are doing great.