One injustice I experienced..two classes were put together to have an art lesson.A4 art paper was passed round the class.Class started their landscapes.One boy went to get a second piece of paper having made a mess first time.When the art master saw this he exploded...He then punished the whole class with his leather belt.
I never forgot this...and saw no good in it then or now.

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In Scotland a leather strap was used to punish schoolchildren.It had cuts to make the end have several ends.This was banned in the 1970's.

A teacher is trained and should adopt a stance of professionalism and self control.