It turns out that parents are right to nag: To succeed in school, kids should do their homework.
Duke University researchers have reviewed more than 60 research studies on homework between 1987 and 2003 and concluded that homework does have a positive effect on student achievement.
Harris Cooper, a professor of psychology and director of Duke's Program in Education, said the research synthesis that he led showed the positive correlation was much stronger for secondary students --- those in grades 7 through 12 --- than those in elementary school.
"With only rare exception, the relationship between the amount of homework students do and their achievement outcomes was found to be positive and statistically significant," the researchers report in a paper that appears in the spring 2006 edition of "Review of Educational Research."
Cooper is the lead author; Jorgianne Civey Robinson, a Ph.D. student in psychology, and Erika Patall, a graduate student in psychology, are co-authors. The research was supported by a grant from the U.S. Department of Education.
While it's clear that homework is a critical part of the learning process, Cooper said the analysis also showed that too much homework can be counter-productive for students at all levels.
"Even for high school students, overloading them with homework is not associated with higher grades," Cooper said.
Cooper said the research is consistent with the "10-minute rule" suggesting the optimum amount of homework that teachers ought to assign. The "10-minute rule," Cooper said, is a commonly accepted practice in which teachers add 10 minutes of homework as students progress one grade. In other words, a fourth-grader would be assigned 40 minutes of homework a night, while a high school senior would be assigned about two hours. For upper high school students, after about two hours' worth, more homework was not associated with higher achievement.
The authors suggest a number of reasons why older students benefit more from homework than younger students. First, the authors note, younger children are less able than older children to tune out distractions in their environment. Younger children also have less effective study habits.
But the reason also could have to do with why elementary teachers assign homework. Perhaps it is used more often to help young students develop better time management and study skills, not to immediately affect their achievement in particular subject areas.
"Kids burn out," Cooper said. "The bottom line really is all kids should be doing homework, but the amount and type should vary according to their developmental level and home circumstances. Homework for young students should be short, lead to success without much struggle, occasionally involve parents and, when possible, use out-of-school activities that kids enjoy, such as their sports teams or high-interest reading."
Cooper pointed out that there are limitations to current research on homework. For instance, little research has been done to assess whether a student's race, socioeconomic status or ability level affects the importance of homework in his or her achievement.
This is Cooper's second synthesis of homework research. His first was published in 1989 and covered nearly 120 studies in the 20 years before 1987. Cooper's recent paper reconfirms many of the findings from the earlier study.
Cooper is the author of "The Battle over Homework: Common Ground for Administrators, Teachers, and Parents" (Corwin Press, 2001).