I canNOT believe that a list of the 5 greatest movie teachers does not even mention The Prime of Miss Jean Brodie.
Once you watch Maggie Smith proclaim, "It is true I am a strong influence on my girls. I am proud of it! I influence them to be aware of all the possibilities of life... of beauty, honor, courage. I do not, Miss Mackay, influence them to look for slime where it does not exist! I am going. When my class convenes, my pupils will find me composed and prepared to reveal to them the succession of the Stuarts," you are changed forever. And you begin to appreciate the power of the bouffant.
One other movie teacher bizarrely overlooked: Professor Taub in The Sure Thing. Though it's a limited role, Viveca Lindsfors is unforgettable and does more for reading glasses than I can possibly say.