I cannot count the number of times I've heard the simple adage:
To play higher, use faster air. To play lower, use more air, but slower.
And unfortunately, this statement is just as confusing to the student the 100th time they hear it as it was the first time.
So how exactly are these two statements different? If you're using a faster airstream, aren't you also using more air? Are there other factors at play (aperture size, for instance) that help clarify the distinction?
I would also be curious to hear other, more helpful ways of imparting this information to a student.