The optimal amount of homework for 13-year-old students is about an hour a day, a study published earlier this month in the Journal of Educational Psychology suggests. And spending too much time on homework is linked to a decrease in academic performance.
Researchers from the University of Oviedo administered surveys to 7,725 Spanish secondary school students, asking about how many days per week they did homework, how much time they spent on it, how much effort they put in, and how much help they received. The students also took a test with 24 math and 24 science questions.
Students who did homework more frequently—i.e., every day—tended to do better on the test than those who did it less frequently, the researchers found. And even more important was how much help students received on their homework—those who did it on their own performed better than those who had parental involvement. (The study controlled for factors such as gender and socioeconomic status.)
The researchers also found that prior knowledge—measured by previous letter grades—was a better predictor of test performance than any homework factor.
Regarding the amount of time students spent on homework, the results were a bit more complicated.
Overall, students spent on average between one and two hours a day doing homework from all subjects.
Those who spent about 90 to 100 minutes a day on homework scored highest on the assessment—however, they didn’t outperform their peers who spent less time on homework by much. The researchers therefore determined that going from 70 minutes of homework a day to 90 minutes a day is not an efficient use of time. “That small gain requires two hours more homework per week, which is a large time investment for such small gains,” they wrote. “For that reason, assigning more than 70 minutes homework per day does not seem very efficient, as the expectation of improved results is very low.”
And after 90 to 100 minutes of homework, they found, test scores declined. The relationship between minutes of homework and test scores is not linear, but curved.
“The key is that the optimum time is about 60 or 70 minutes [of homework] a day,” Javier Suarez-Alvarez, co-lead researcher on the study, said in an interview.
The study does, of course, come with some caveats. As the researchers note, the results are not causal; they only show a correlation between homework and test scores. Also, the survey did not distinguish between math and science homework. Suarez-Alvarez said the study also brings up questions about how factors like “academic intelligence, self-concept, and self-esteem” play into academic performance.
Even so, the study offers some insights that middle school teachers may find helpful. “Our data indicate that it is not necessary to assign huge quantities of homework, but it is important that assignment is systematic and regular, with the aim of instilling work habits and promoting autonomous, self-directed learning,” the researchers write.
Or as Suarez-Alvarez put it, “Maybe it’s more important how they do the homework than how much.”
Chart: From “Adolescents’ Homework Performance in Mathematics and Science: Personal Factors and Teaching Practices,” Journal of Educational Psychology , March 16, 2015.
A version of this news article first appeared in the Curriculum Matters blog.