The National Education Association's 2016-17 Rankings & Estimates report says that in 2016, there were 49,831,699 students in public schools and 3,131,326 public school teachers—a ratio of 15.9 students per teacher.
In individual states, the ratio ranged from 11.7 students per teacher in Vermont to 25.7 students per teacher in Nevada.
Here is a list of the 10 states that had the highest student-teacher ratios in 2016.
