Updated on Dec 23, 2009

Homework can be defined as tasks assigned to students by teachers that are intended to be carried out during nonschool hours. This definition excludes (a) in-school guided study (although homework is often worked on during school); (b) home study courses, and (c) extracurricular activities such as sports teams and clubs.


According to Harris Cooper (2007), the most common variation in homework assignments relates to its content or subject matter. Independent of content, homework assignments also vary in their purpose or goal. Practice homework assignments ask students to go over material already presented in class so as to reinforce learning and facilitate mastery of specific skills. Preparation assignments introduce material that will be presented in future lessons. These assignments aim to help students obtain the maximum benefit when the new material is covered in class. Extension homework involves the transfer of previously learned skills to new situations, such as asking students to apply their mathematics knowledge to construct a household budget. Finally, integration homework requires the student to apply separately learned skills to produce a single product, such as reading a book and writing a report on it.

Homework also can serve purposes that do not relate directly to instruction. Homework can be used to (a) establish communication between parents and children, (b) fulfill directives from school administrators, (c) punish students, and (d) inform parents about what is going on in school. Most homework assignments have elements of several different purposes.

Assignments can vary in many other ways, including the skill area covered (e.g., reading, writing, math), the level of difficulty, and the time required for completion. With regard to the latter, the amount of homework students are assigned can best be thought of in terms of (a) the frequency, or how often, homework is assigned and (b) the duration of each assignment, or how long it takes to complete each assignment. For example, two students doing four hours of homework a week might be having very different homework experiences. One might be doing one hour of homework on each of four nights while the other is doing two hours of homework on just two nights.


The most direct positive effect of homework is that it can improve the retention and understanding of academic material. More indirectly, homework can improve students' study skills and attitudes toward school (by showing how skills that are learned in school have application to activities students enjoy doing outside school) and can teach students that learning can take place anywhere, not just in school buildings. The nonacademic benefits of homework include fostering independent and responsible character traits. Finally, homework can involve parents in the school process, enhancing their appreciation and understanding of what goes on in the classroom and allowing them to express positive attitudes toward the value of school success.

Homework can have negative effects as well. It can lead to boredom with schoolwork if students are required to spend too much time on academic material. Homework can deny students access to leisure time and community activities that also teach important life skills. Parent involvement in homework can turn into parent interference. For example, parents can confuse their child if the instructional techniques they use at home differ from those used by teachers. Homework can lead to the acquisition of undesirable character traits if it promotes cheating, either through the copying of assignments or if the student receives help with homework that goes beyond tutoring. Finally, homework could accentuate existing social inequities. Diane Scott-Jones has argued that children from dis-advantaged homes may have more difficulty completing assignments than their middle-class counterparts.

Homework can reinforce concepts taught in the classroom.Homework can reinforce concepts taught in the classroom.ANDY SACKS/STONE/GETTY IMAGES.


Research on homework generally supports the notion that it helps students learn academic material, but with important qualifications. Cooper, Jorgianne Robinson, and Erika Patall have conducted, since 1984, six studies that used two groups of students who were on average as similar as possible—by randomly assigning students to groups, statistically controlling for student differences, or matching a student in one group with a similar student in the other group while eliminating students who did not have a good match—and then manipulated whether students did or did not receive homework assignments. These studies provide a clear picture that homework can be effective in improving students' scores on unit tests (the class tests that come at the end of a topic unit). Students doing homework in second grade did better on number places, third and fourth grade did better on English skills and vocabulary, fifth grade on social studies, high school on American history, and twelfth graders on Shakespeare. Across five studies, the average (50th percentile) student doing homework had a higher unit test score than 73% of students not doing homework.

A second type of study supports the conclusion that students who do homework perform better on tests. This type simply asked students (or one of the students' parents) how much homework the students did; no manipulation of homework assignments was involved. However, these studies attempted to statistically equate students on other characteristics that might be associated with homework and achievement and therefore might account for any relationship between the two. Because they do not purposively manipulate homework, these studies can never lead to as confident a conclusion about homework's direct effect on achievement. However, they do typically involve large nationally representative samples of students such as the National Educational Longitudinal Study. Also, these studies typically use broader measures of achievement than unit tests, such as cumulative grades and standardized test scores. Twelve such studies have tested more than 30 different statistical models. The other factors that might influence achievement (and time on homework) that were controlled for in the statistical models included numerous student factors (for example, sex, ethnicity, ability, motivation), family factors (for example, wealth, parent involvement), school factors (for example, subject matter, teacher training, class size), and other student behaviors (for example, TV watching, extracurricular activities and jobs, absences from school). Achievement was measured for all sorts of content areas using all types of achievement measures. In 11 of the 12 samples, the link between time on homework and achievement was positive.

A third type of study that looked at homework involved no attempt to purposively vary homework or to equate students on other characteristics that might explain any relationship. Thus, these correlational studies can make no claims about a causal link between homework and achievement. Though not conclusive, this type of evidence can give important clues about when, where, and for whom homework might be more or less effective. In 35 samples of students used in correlational studies, 27 found the link between homework and achievement was a positive one; in 8, it was negative.

The correlational results were noticeably different depending on the grade level of the students. The average correlation between time spent on homework and achievement was substantial for secondary school students but for elementary school students, it hovered around no relationship at all. There are several possible explanations for this finding. First, cognitive psychologists Dana Plude, James Enns, and Darlene Broudeur suggest that younger children are less able to tune out distractions. It is easy to imagine that the distractions present in a younger student's home would make studying there less effective for them than for older students. Second, a study by Annette Dufresne and Akira Kobasigawa suggests that younger students have less well-developed study habits. Their study showed that older students spend more time than younger ones working on harder items. Older students were also more likely to use self-testing strategies to monitor how much of the material they have learned.

Other explanations for the weak correlation between homework and achievement in early grades are possible. A study by Laura Muhlenbruck, Cooper, Barbara Nye, and James Lindsay found evidence suggesting teachers in early grades may assign homework more often to develop young students' management of time—a skill rarely measured on standardized achievement tests or graded in class. This study also provided some evidence that young students who are struggling in school take more time to complete homework assignments. Thus, while it seems highly likely that age difference in attention span and study habits can be applied to the homework situation, it is also likely that poor-achieving young children spend more time on homework simply because it is more difficult for them.


Based on these results and the experience of teachers, consensus has emerged regarding rough guidelines for the amount of homework that should be assigned to students in different grade levels. The National PTA and the NEA suggest that homework for children in grades K-2 is most effective when it does not exceed ten to twenty minutes each day. In grades 3 through 6, children can benefit from 30 to 60 minutes per day. Junior high and high school students can benefit from more time on homework and the amount might vary from night to night. These recommendations are consistent with the conclusions reached by studies of the effectiveness of homework.

In conclusion, homework can be an effective instructional device. However, both experience and research suggest that the relationship between homework and achievement is influenced greatly by the students' developmental level. Expectations for homework's effects, especially in the short term and in earlier grades, must be modest. Further, homework can have both positive and negative effects depending on how it is used, with whom, and in what context.


Cooper, H. (2007). The Battle over Homework: Common Ground for Administrators, Teachers, and Parents (3rd ed.). Thousand Oaks, CA: Corwin Press.

Cooper, H., Robinson, J., & Patall, E. (2006). Does homework improve academic achievement?: A synthesis of research, 1987–2003. Review of Educational Research, 76, 1–62.

Dufresne, A., & Kobasigawa, A. (1989). Children's spontaneous allocation of study time: Differential and sufficient aspects. Journal of Experimental Child Psychology, 42, 274–296.

Mulhenbruck, L., Cooper, H., Nye, B., & Lindsay, J. (1999). Homework and achievement: Explaining the different strengths of relation at the elementary and secondary school levels. Social Psychology of Education, 3, 295–317.

National Parent Teacher Association and National Education Association. Help Your Student Get the Most Out of Homework. Retrieved April 17, 2008, from

Plude, D., Enns, J., & Brodeur, D. (1994). The development of selective attention: A life-span overview. Acta Psychologica, 86, 227–272.

Scott-Jones, D. (1984). Family influences on cognitive development and school achievement. In E. Gordon (Ed.), Review of Research in Education, Vol. 11. Washington, DC: American Educational Research Association.

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