“Enjoy your school days, they’re the best years of your life”

What is it with teachers and having chips on their shoulders? I know I begin with a big statement and, as always, I do not mean this as a broad sweeping statement applying to all in the field. Quite the opposite, I have had some very good experiences with teachers, some I even idolised; but it seems to me from some of my not so good experiences and from listening to the experiences of others that a high percentage of teachers seem to have some sort of chip on their shoulder that they then take out on students.