Data Annotations - InverseProperty Attribute
public class Course
{
    public int CourseId { get; set; }
    public string CourseName { get; set; }
    public string Description { get; set; }
    public Teacher OnlineTeacher { get; set; }
    public Teacher ClassRoomTeacher { get; set; }
}
public class Teacher
{
    public int TeacherId { get; set; }
    public string Name { get; set; }
    [InverseProperty("OnlineTeacher")]
    public ICollection<Course> OnlineCourses { get; set; }
    [InverseProperty("ClassRoomTeacher")]
    public ICollection<Course> ClassRoomCourses { get; set; }
}
