Note: Data are for public noncharter schools and are based on a count of schools, not on the total number of vacancies or the number of teachers the school failed to hire. All principals are asked whether their school has or does not have any vacancies (“teaching positions for which teachers were recruited and interviewed by this school’s hiring authority”). The shares reported in the table represent the share of schools that had any vacancies, and, for those with vacancies, the share of schools that could not fill a vacancy in at least one of the fields listed on the questionnaire, and the share of schools that filled a vacancy but found it "very difficult"  in at least one of the fields. Fields included were: (1) general elementary, (2) special education, (3) English or language arts, (4) social studies, (5) computer science, (6) mathematics, (7) biology or life sciences, (8) physical sciences, (9) ESL or bilingual education, (10) foreign languages, (11) music or art, (12) career or technical, and (13) other. A principal is in a low-poverty school if less than 25 percent of the student body in his/her school is eligible for free or reduced-price lunch programs; a principal is in a high-poverty school if 50 percent or more of the student body is his/her school is eligible for those programs.