In this subtitle the following words have the meanings indicated. “Career ladder” means the career ladder for public prekindergarten, primary, or secondary school teachers in the State implemented by county boards that meets the standards set forth under this subtitle and the standards adopted by the Department. “NBC” means National Board Certification issued by the National Board for Professional Teaching Standards. “NBC teacher” means a teacher who holds an active National Board Certification. “Teacher” means a certified public school employee who is primarily responsible and accountable for teaching the students in the class. “Teacher” does not include, unless otherwise provided: Curriculum specialists; Instructional aides; Attendance personnel; Psychologists; Social workers; Clerical personnel; An individual with a Resident Teacher Certificate; or An individual with a certification for career professionals.