Airspeed alone means nothing with regard to when or whether the
airplane will stall. We need to think in terms of airspeed AND G-load
-- these are the two parameters that will give us a clue as to our
margin to the stall, or whether or not we are moving closer to, or
farther from, critical angle of attack.
......But won't airspeed alone change the "cushion" that you have to maneuver
with? A steep turn at 90 kts isn't usually a problem. Doing something like
that near Vso on final will almost certainly be one. As you point out, at
lower airspeeds the aircraft will stall with less of a load.
I don't dispute that there's more to stalls than airspeed. I just think
you're all putting too fine a point on this. If the hypothetical instructor
said, "Watch your airspeed, or you'll reduce the amount of G-load that the
airplane can handle and may invoke a stall if you decide to maneuver
drastically", then you probably wouldn't have a problem with it, but in the
time it took to say all that, the instructor and student would be hitting
the ground! Proper instruction of what causes a stall is one thing. Not
letting your student get out of control on an approach is another.
Let's "approach" this another way: You're the instructor in this case. Do
you want your student to maintain a certain airspeed on approach? If so,
why? And if they allow the plane to get below that speed, what are you going
to say to them?
Student Pilot @ UES