Is homework good for your child’s brain?

Around this time of year, as days get longer and the weather more inviting, kids who hate homework hate it with a passion. That’s not new.

But homework-hating kids have been gaining allies in the grown-up world in recent years, with authors of books with titles like "The Homework Myth," and "The Case Against Homework," arguing homework is a waste of time — or worse, just plain bad for kids.

But what does science have to say?

If you want to talk to a neuroscientist about homework, Harris Cooper of Duke University is the guy. Not only does he study how kids study: He studies the studies of how kids study. Back in the '80s, he went through all the research he could find about homework and achievement. Turns out they're connected — but Cooper says with kids, you can’t take a one-size-fits-all approach.

"Both the amount and type of homework does and should vary as a function of the child’s age," Cooper says.

At the grade school level, there’s not much to show that homework helps prime the brain.

"Young children have a limited attention span," Cooper says. "In particular they have trouble tuning out distractions and most parents will know that, so that if homework assignments go on for too long, it’s not surprising to discover that a child’s brain is wandering off."

But the research shows that, gradually, as kids get older, homework starts to pay off — and the optimum amount of time spent on homework increases with age.

"So I’ve been to schools and school districts where I’ve shown the curves that suggest that in elementary school the curve is pretty flat, in middle school it optimizes, tops out at about the 60-90 minutes and then in high school it tops out at about 2 hours," Cooper says. "And many years ago I had a teacher walk up to me and say that sounds like the 10-minute rule— and I says, 'Yep, you know, you’re right.'"

Long before Cooper published his research, the "10-minute rule" had been conventional wisdom among teachers.

"To decide how much homework their children should be taking home, they take the grade level and multiply by 10," Cooper says. "This is a part of teachers' craft, knowledge, and it is consistent with the limited research, but it is consistent with the research that we have."

Despite the fact that neuroscientists and teachers agree on this point, in the last 60 years, there’s actually been an increase in homework for the earliest primary grades.

"That’s largely a function of teachers feeling greater pressure because of end-of-grade tests in the third grade — kids should be able to read by then — and also because of research that shows early reading is very important to later success," Cooper says.

Over the same period, older kids also saw their homework load increase, Cooper says, thanks to competition to get into the best colleges.

Dover-Sherborn High School began a program to reduce student stress in 2014. The school's guidance director, Ellen Chagnon, says college pressure pushes students to go far beyond the basic academic requirements.

"We have students who do a whole lot of homework because they're taking challenging classes that have more homework. Then they’re involved in different sports, extracurriculars, tutoring, lessons, whatever it might be, so their days are feeling very full," Chagnon says.

The school has now taken an inventory of how long it takes students to complete all the different assignments they’re given, and teachers coordinate with each other to make sure students aren’t overloaded across multiple classes.

"Some teachers are giving a no-homework night here and there, where before, they felt maybe they couldn’t do that because the pressure you always must give homework," she says. "But some of them are bringing something they might have assigned to homework into their school class, doing a warmup activity with it, or a closing activity with it kind of interweaving it that way, too."

Chagnon hopes these changes will let the kids enjoy life while they keep learning, or, in other words, restore a sense of balance.

A version of this story first appeared on WGBHNews.org.