Yes, the noun 'teacher' is a common noun, a Word for any teacher anywhere.
A proper noun is the name of a specific person, place, thing, or a title; for example:
- Rebecca Mielwocki, the Council of Chief State School Officers 2012 National Teacher of the Year
- Teacher Street, West Monroe, LA or Teacher Lane, Four Corners, FL
- Teacher Heaven (teaching supplies), Houston, TX
- "One Teacher", 2002 documentary film by Mark Keegan
- "The Math Teacher Is Dead", a novel by Robert Manners
