Is the word TEACHER a title like MR, DOCTOR, etc? If so, can I use it without the last name as in Teacher David? or must I use it as in Teacher David Brown or Teacher Brown?
"Professor," however, is used as a title. I believe there are various rules that differ from country to country about when an individual is entitled, no pun intended, to the honor of being addressed as "Professor Smith." But I do not know these rules :(
[Disclaimer: I am a native speaker but do not teach]