My school days were in a time of academic gowns and mortar boards for masters and sets with gowns for mistresses.Cue, arrival of the American teacher who wore an open-neck shirt with an unfastened tie and an old, very old, sports jacket. Without doubt the best maths teacher I have ever encountered. He had a gown but this never left the hook by the blackboard.I don't give a damn what a teacher wears if they have the nous to command discipline and can impart knowledge. To focus on this shows, IMHO, that there are far deeper issues in the establishment where the OP lectures.
Nigel Brooks ● 4152d