What this exercise really does is demonstrate how angle of attack is
decoupled from attitude. It's unfortunate that the concept of pitch
control by reference to angle attack is only taught at a basic
theoretical level in most gliding instruction - undoubtedly due to the
lack of any angle of attack indicator on gliders! (unless you count the
pitot mast -mounted yaw string on a 2-33).

I really wish there was a simple, reliable and easy to read angle of
attack (AOA) gauge available for gliders, optimized for efficient
thermalling (no adjustment needed for water ballast or bank angle -
unlike airspeed) and safe pattern speeds (instant response to wind
gradient and shear; and again automatically adjusts for landing right
off tow while still full of water).

Then you could use this exercise to show how to drive the AOA way past
the stalling AOA while still appearing to be in a level "flying"
attitude.

Kirk