Student engagement is crucial in an on-line environment because there is no face to face, verbal and nonverbal communication present. Therefore, the instructor must have good writing skills to effectively communicate the expectations to the students. The correspondence must include motivating and encouraging comments to inspire the students to perform well.
In addition the instructor should post their office hours / hours of availability to allow the students the opportunity to ask detailed questions.
Usually when the students know that the instructor is present and available to assist they tend to be engaged in the course.