Communication is key whether online or in person. Learning how to communicate effectively via email, chats sessions, IM, or other formats is important for the students as well as for the instructor. I have learned a bit about the different methods (and word smithing) to use when communicating with students. As I have stated to students who come out of my program and go on an interview to obtain a job-"You never get a second chance at making a first impression" -so bring your A game to the meeting. This is also true when meeting students online or inperson for the first time. I believe it is also important to address students as their name appears on the school records and allow students to correct you if they prefer to be called something else. (ex. a student's first name is Jackson but they state they would like to be called Jack hence it would be noted).
