Americans will be critical of you if you are living in the United States and do not speak at least some English.  I will teach you American slang which is not taught in the schools.  I will help you to speak conversational English which will boost your self-confidence in conversing easily with business people, school system employees, and others you meet on a daily basis.  I will teach you how to order food off of a menu written in English so you will feel confident when you eat out at an American restaurant.