Note: Data are for teachers in public noncharter schools in the 2011–2012 Schools and Staffing Survey (SASS). Teachers who quit are those who generated a vacancy in the 2012–2013 school year and are not in the profession (they left teaching, were on long-term leave, or were deceased). According to research and to the U.S. Department of Education, highly qualified teachers have the following four credentials: They are fully certified (with a regular, standard state certificate or advanced professional certificate versus not having completed all the steps); they took a traditional route into teaching (participated in a traditional certification program versus an alternative certification program, the latter of which is defined in the teacher survey questionnaire as “a program that was designed to expedite the transition of nonteachers to a teaching career, for example, a state, district, or university alternative certification program”); they are experienced (have more than five years of experience); and they have a background in the subject of main assignment; i.e., they have a bachelor's or master's degree majoring in the main teaching assignment field (general education, special education, or subject-matter specific degree) versus having no educational background in the subject of main assignment. The figure also provides information on an additional qualification—certification by the National Board for Professional Teaching Standards (NBPTS) in at least one content area. A teacher is in a low-poverty school if less than 25 percent of the student body in his/her class is eligible for free or reduced-price lunch programs; a teacher is in a high-poverty school if 50 percent or more of the student body she/he teaches are eligible for those programs. Teaching status is determined by the reported status of teachers in the Teacher Follow-up Survey conducted for the 2012–2013 school year, one year after the Schools and Staffing Survey.