Across the U.S., schools place varying emphasis on homework. Even within a single district or school, homework expectations can vary widely depending on the teacher. While some first graders are slaving away for an hour each night, some second graders might be getting by with almost no outside work. So what role does homework play in learning? And how much is too much — or too little?

According to Harris Cooper, a psychology professor at Duke University, homework is valuable to a point, and researchers have found that some kinds provide more benefits than others. Homework may be most useful as a way to develop study habits and practice skills that can be acquired through repetition, he says. Think spelling, vocabulary, multiplication tables, number placement, and grammar rules for foreign languages: “The biggest homework effects do come from these kinds of skill areas.”

As for what constitutes an appropriate amount, one easy-to-remember tip is Cooper’s “10-minute rule,” which calls for 10 minutes of homework per day per grade and is endorsed by the National Education Association. Looking for more grade-by-grade guidelines? GreatSchools weighs in with this primer on how much homework is best.

Kindergarten homework

None. The fact is that a lot of kindergarten teachers assign homework. When New York Times Magazine writer Peggy Orenstein took an informal survey of her local schools, she found that every one boasted daily homework requirements for kindergartners. But studies have shown homework has few benefits for young kids and could even have negative effects (in The Battle Over Homework, Cooper found that assigning homework in elementary school did not improve test scores and that too much of it decreased motivation). Then there’s Finland, where students perform at or near the top of all countries on standardized tests, and children don’t even begin school until age 7. So instead of worrying about homework in kindergarten, involve your children in family activities to boost their brainpower, like talking, playing pretend, and reading together before bed. Just setting aside time for conversations can be an incredibly valuable way to connect with your child.

1st grade homework

0-10 minutes. Again, the jury’s still out on whether homework helps at this young of an age. If it does, it’s in the hard-to-measure areas of study skills and time management. Reviewing the current homework debate, Slate senior editor Emily Bazelon has made the case that no elementary school student should be required to do homework, so spend time playing, talking, and interacting as a family. With some brainstorming, everyday activities like eating, driving, or shopping can be turned into opportunities for learning.

2nd grade homework

0-20 minutes. In second grade, continue to cook together, play games as a family, and spend time outside. Depending on the school and teacher, your child’s homework may increase somewhat. That’s OK, but don’t let your kid spend excessive amounts of time on assignments— more than 20 minutes per night is probably overkill. On the other hand, second grade is not too early to encourage your child to start reading age-appropriate books on his or her own, whether they’re pretty picture books or the Harry Potter series. Either way, it’s important for children to develop good reading habits at this age, A good rule of thumb is at least 15 minutes of reading time every night (together or alone), even if it’s not part of their homework. Know your child’s interests and recommend a few books to match. Studies have shown that even a little bit of time spent reading increases children’s comprehension, vocabulary, and understanding of the larger world.