When I was doing research for my book, I found that everyone, including the National PTA and the National Education Association referred to the 10-minute rule, but I never did discover its origin. But in reading the pieces on GreatSchools, I discovered that so-called homework guru, Harris Cooper, made it up out of whole cloth:
So how can you know if your child is doing the right amount? Who came up with that 10-minutes-per-grade rule that’s become the accepted norm? (And if that is the magic number, why is my neighbor’s 8-year-old daughter doing two-plus hours a night?)
The oft-bandied rule on homework quantity — 10 minutes a night per grade (starting from between 10 to 20 minutes in first grade) — is ubiquitous. Indeed, go to the National Education Association’s website or the national Parent Teacher Association’s website, and 10 minutes per grade is the recommended amount for first through 12th grade.
But where did it come from? “The source [of that figure] was a teacher who walked up to me after a workshop I did about 25 years ago,” says Cooper. “I’d put up a chart showing middle school kids who reported doing an hour to an hour and a half were doing just as well as high schoolers doing two hours a night. The teacher said, ‘That sounds like the 10-minute rule.’” He adds with a laugh, “I stole the idea.”