In my secondary school, the frequency of slippering varied hugely between teachers, which in itself is probably a bit unfair. We all knew who the 'heavy hitters' were, Timetabling and form mistress allocation meant you couldn't avoid them, but if you were pain-averse, you would deliberately set your behaviour level to 11 in their classes. But even with this knowledge, my recollection of how often you would see a girl getting the slipper aligns more with Sharon's experience. And what was it with PE/Sports mistresses! They DID slipper with abandon. @
jennypenny