Average public school class size: Average class size in public K–12 schools, by school level, class type, and state: 2020–21

! Interpret data with caution. The coefficient of variation (CV) for this estimate is between 30 percent and 50 percent (i.e., the standard error is at least 30 percent and less than 50 percent of the estimate).

‡ Reporting standards not met. Either there are too few cases for a reliable analysis, or the coefficient of variation (CV) for this estimate is 50 percent or greater (i.e., the standard error is 50 percent or more of the estimate).

NOTE: Data are weighted estimates of the population. Elementary schools offer at least one grade of K through 4, and the number of elementary grades is higher than the number of middle grades. Middle schools offer at least one of grades 5 through 8, and the number of middle grades is greater than the number of elementary or secondary grades. Secondary/high schools are defined as schools that enroll students in more of grades 9 through 12 than in lower grades. Combined/other schools include all other combinations of grades, including K–12 schools. School level categories in the 2020–21 NTPS differ from those in previous survey administrations; caution should be exercised when comparing estimates by level over time. Self-contained classes are defined as instruction to the same group of students all or most of the day in multiple subjects, and departmentalized instruction is defined as instruction to several classes of different students most or all of the day in one or more subjects. Among all public school teachers, 25 percent teach self-contained classes in elementary schools, 1 percent in middle schools, 1 percent in secondary/high schools, and 2 percent in combined/other grade schools; 6 percent teach departmentalized classes in elementary schools, 15 percent in middle schools, 24 percent in secondary/high schools, and 4 percent in combined/other grade schools. In addition, teachers could teach other types of classes, such as elementary subject specialist classes, team-taught classes, and “pull-out” or “push-in” classes (14 percent in elementary schools, 2 percent in middle schools, 2 percent in secondary/high schools, and 2 percent in combined/other grade schools). Type of teaching arrangement does not sum to 100 percent because of rounding.

SOURCE: U.S. Department of Education, National Center for Education Statistics, National Teacher and Principal Survey (NTPS), "Public School Teacher Data File," 2020–21.