Spending more than two hours a night doing homework is linked to achieving better results in English, maths and science, according to a major study which has tracked the progress of 3,000 children over the past 15 years.
Spending any time doing homework showed benefits, but the effects were greater for students who put in two to three hours a night, according to the study published by the Department for Education.
The finding on homework runs counter to previous research which shows a "relatively modest" link between homework and achievement at secondary school.
The academics involved in the latest research say their study emphasises what students actually do, rather than how much work the school has set.
Pam Sammons, a professor of education at Oxford University, said that time spent on homework reflected the influence of the school – whether pupils were expected to do homework – as well as children's enjoyment of their subjects.
Sammons said: "That's one of the reasons Indian and Chinese children do better. They tend to put more time in. It's to do with your effort as well as your ability.
"What we're not saying is that everyone should do large amounts, but if we could shift some of those who spend no time or half an hour into [doing] one to two hours – one of the reasons private schools' results are better is that there's more expectation of homework."
The study controlled for social class, and whether pupils had a quiet place in which to do their homework, but still found a benefit, Sammons said.
The research was conducted by academics from the Institute of Education, Oxford and Birkbeck College, part of the university of London. It has tracked around 3,000 children from pre-school to the age of 14.
It also finds that students who reported that they enjoyed school got better results. "This is in contrast to findings during primary school where 'enjoyment of school' was not related to academic attainment," researchers said.
Schools could ensure children had a better experience by improving the "behavioural climate", making schoolwork interesting and making children feel supported by teachers, Sammons said.
The research shows that working-class parents can help their children succeed "against the odds" by having high aspirations for them.
Children who did well from disadvantaged backgrounds were backed by parents who valued learning and encouraged extra-curricular activities. "Parents' own resilience in the face of hardship provided a role model for their children's efforts," the research says.
The study underlines the importance of a good primary school. Children who attended an "academically effective" primary school did better at maths and science in later life. The study did not find a link with performance in English.
Ministers have scrapped guidelines setting out how much homework children should be set amid criticism that it can interfere with family life.
Under the last government, guidance was issued to all schools recommending they have a policy on homework.
The guidelines suggested children aged five to seven should be set an hour a week, rising to half an hour a night for seven- to 11-year-olds. Secondary schools were encouraged to set up to two and a half hours a night for children aged 14-16.
Scrapping the guidelines frees headteachers to set their own homework policy, the government says.
A Stanford education researcher found that too much homework can negatively affect kids, especially their lives away from school, where family, friends and activities matter.
"Our findings on the effects of homework challenge the traditional assumption that homework is inherently good," wrote Denise Pope, a senior lecturer at the Stanford Graduate School of Education and a co-author of a study published in the Journal of Experimental Education.
The researchers used survey data to examine perceptions about homework, student well-being and behavioral engagement in a sample of 4,317 students from 10 high-performing high schools in upper-middle-class California communities. Along with the survey data, Pope and her colleagues used open-ended answers to explore the students' views on homework.
Median household income exceeded $90,000 in these communities, and 93 percent of the students went on to college, either two-year or four-year.
Students in these schools average about 3.1 hours of homework each night.
"The findings address how current homework practices in privileged, high-performing schools sustain students' advantage in competitive climates yet hinder learning, full engagement and well-being," Pope wrote.
Pope and her colleagues found that too much homework can diminish its effectiveness and even be counterproductive. They cite prior research indicating that homework benefits plateau at about two hours per night, and that 90 minutes to two and a half hours is optimal for high school.
Their study found that too much homework is associated with:
• Greater stress: 56 percent of the students considered homework a primary source of stress, according to the survey data. Forty-three percent viewed tests as a primary stressor, while 33 percent put the pressure to get good grades in that category. Less than 1 percent of the students said homework was not a stressor.
• Reductions in health: In their open-ended answers, many students said their homework load led to sleep deprivation and other health problems. The researchers asked students whether they experienced health issues such as headaches, exhaustion, sleep deprivation, weight loss and stomach problems.
• Less time for friends, family and extracurricular pursuits: Both the survey data and student responses indicate that spending too much time on homework meant that students were "not meeting their developmental needs or cultivating other critical life skills," according to the researchers. Students were more likely to drop activities, not see friends or family, and not pursue hobbies they enjoy.
A balancing act
The results offer empirical evidence that many students struggle to find balance between homework, extracurricular activities and social time, the researchers said. Many students felt forced or obligated to choose homework over developing other talents or skills.
Also, there was no relationship between the time spent on homework and how much the student enjoyed it. The research quoted students as saying they often do homework they see as "pointless" or "mindless" in order to keep their grades up.
"This kind of busy work, by its very nature, discourages learning and instead promotes doing homework simply to get points," said Pope, who is also a co-founder of Challenge Success, a nonprofit organization affiliated with the GSE that conducts research and works with schools and parents to improve students' educational experiences..
Pope said the research calls into question the value of assigning large amounts of homework in high-performing schools. Homework should not be simply assigned as a routine practice, she said.
"Rather, any homework assigned should have a purpose and benefit, and it should be designed to cultivate learning and development," wrote Pope.
In places where students attend high-performing schools, too much homework can reduce their time to foster skills in the area of personal responsibility, the researchers concluded. "Young people are spending more time alone," they wrote, "which means less time for family and fewer opportunities to engage in their communities."
The researchers say that while their open-ended or "self-reporting" methodology to gauge student concerns about homework may have limitations – some might regard it as an opportunity for "typical adolescent complaining" – it was important to learn firsthand what the students believe.
The paper was co-authored by Mollie Galloway from Lewis and Clark College and Jerusha Conner from Villanova University.
Clifton B. Parker is a writer at the Stanford News Service.