To see that you become a teacher in your dream signifies that a person whom you help will be successful in his/her exam, s/he will get in someone’s good books in his office thanks to your help.
To give your teacher a hug or your teacher is listening to you in your dream denotes that as a result of your decision, people will be happy.
To see your old teacher in your dream may represent that you will want help from your old friend in order to strengthen your authority and you will find support from this person.