Twenty-two states still allow corporal punishment in school: 15 expressly permit it while another seven do not prohibit it. That's according to a recent letter written by U.S. Secretary of Education John B. King Jr. to the nation's governors and state school chiefs.

Not sure what, exactly, corporal punishment is? Here's a quick primer.

It often involves a paddle. Always, pain. That's the point.

The National Association of School Psychologists explains corporal punishment as "the intentional infliction of pain or discomfort and/or the use of physical force upon a student with the intention of causing the student to experience bodily pain so as to correct or punish the student's behavior."

Lest you think this kind of extreme discipline died with the dunce cap, that letter we mentioned — from Secretary King — decried the fact that, in the 2013-2014 school year, more than were physically punished.

The move comes after an investigation by Education Week into the prevalence of the practice.

"School-sponsored corporal punishment is not only ineffective, it is a harmful practice, and one that disproportionally impacts students of color and students with disabilities," King wrote. "This practice has no place in the public schools of a modern nation that plays such an essential role in the advancement and protection of civil and human rights."

Also this month, dozens of groups, including the National PTA, Children's Defense Fund and American Academy of Pediatrics signed a letter of their own, supporting an end to corporal punishment.

Copyright 2021 NPR. To see more, visit https://www.npr.org.