Whats wrong with teaching them to recognise the onset of buffeting instead.
Nothing, if your aircraft exhibits noticeable pre-stall buffet. There are popular training types that show little obvious buffet (that would be apparent to a student) in the initial stalling exercise from a clean airframe, power off, erect, level flight situation. We demonstrate a suite of signs leading to the stall, all the symptoms of low airspeed including sloppy controls and reducing wind noise, nose high attitude, aft column and lack of ability to maintain altitude (leading to an indicated RoD). We would say in the pre-flight brief that pre-stall buffet is a symptom, but warn that they might not experience it in our aircraft.
Some might say that training should not be conducted in aircraft that do not exhibit all the symptoms or which do not spin etc.
TOO