When I was instructing on gliders (a long time ago!) we felt it was all too easy for pupils to become complacent about spinning, because of the forgiving nature of most training gliders at that time. So we'd routinely put them in the RH seat of a Condor and demonstrate a full three-turn spin and recovery. This was usually enough to create pop-eyed astonishment and a vastly increased awareness! As I recall, the Condor was also excellent for this purpose as it required very positive control inputs to effect the recovery, unlike the aforementioned glider trainers that merely required a bit of foot-shuffling and relaxation of back pressure.