SAN FRANCISCO (KRON/CNN) — A new study supports something many parents have long believed: Children are given too much homework.

With the return of the school year, the stress of getting the school work completed and turned in on time weighs heavily on many families.

Now a new study may help explain some of that stress.

The study, published Wednesday in The American Journal of Family Therapy, found students in the early elementary school years are getting significantly more homework than is recommended by education leaders, In some cases kids are saddled with almost three times as much homework as is recommended.

The standard, endorsed by the National Education Association and the National Parent-Teacher Association, is the so-called “10-minute rule” — 10 minutes per grade level per night. That translates into 10 minutes of homework in the first grade, 20 minutes in the second grade, all the way up to 120 minutes for senior year of high school. The NEA and the National PTA do not endorse homework for kindergarten.

Researchers found children in the first grade had as much as three times the homework load recommended by the NEA and the National PTA.

Parents reported first-graders were spending 28 minutes on homework each night versus the recommended 10 minutes. For second-graders, the homework time was nearly 29 minutes, as opposed to the 20 minutes recommended.

And kindergartners spent 25 minutes a night on after-school assignments, according to the study carried out by researchers from Brown University, Brandeis University, Rhode Island College, Dean College, the Children’s National Medial Center and the New England Center for Pediatric Psychology.

“It is absolutely shocking to me to find out that particularly kindergarten students (who) are not supposed to have any homework at all … are getting as much homework as a third-grader is supposed to get,” said Stephanie Donaldson-Pressman, the contributing editor of the study and clinical director of the New England Center for Pediatric Psychology.

“Anybody who’s tried to keep a 5-year-old at a table doing homework for 25 minutes after school knows what that’s like. I mean children don’t want to be doing, they want to be out playing, they want to be interacting and that’s what they should be doing. That’s what’s really important.”

The study involved questionnaires filled out by more than 1,100 English and Spanish speaking parents of children in kindergarten through grade 12.