The student-teacher ratio can give parents a general idea of a teacher’s workload in a particular school. However, the ratio will not tell you how many students would be in your child’s class. The student-teacher ratio includes all full-time teachers, including art, music, PE, and other specialized positions. A typical class is larger than the ratio suggests. In 2004, the average student-teacher ratio for an elementary school with 300 to 500 students was slightly more than 15 students per teacher, according to the National Center for Education Statistics; the average class size for elementary schools was 20.4.