Parents don't like to see their children struggle. Parents feel the pain of kids who are exasperated when they can't figure out a math problem, and they don't like to see kids bleary-eyed late at night while trying to finish a science project.

Parents don't like to see their children struggle. Parents feel the pain of kids who are exasperated when they can't figure out a math problem, and they don't like to see kids bleary-eyed late at night while trying to finish a science project.

It's natural for parents to want to help. It might start out with a little cutting and pasting while the kids do the intellectual work on, say, a model volcano. But that can lead to the parents' researching and assembling the whole slippery slope.

At what point does parental help cross the line and diminish the task's value for the student?

"The most important thing to remember about homework," says Richard Bavaria, vice president of education at Sylvan Learning Centers, is that it should "reinforce skills that they've learned in the classroom. It's practice."

If children ask for help, parental guidance is OK. Showing them how to research the answer is best, says Bavaria; doing the homework for them is not an option.

"Kids don't want parents to do their homework for them. They might say they do, but most kids know they need to know the information to get them through the rest of the year," he says.

Sometimes students just need parents to talk them through a tough assignment, either by suggesting ways to break it up into more manageable chunks or by helping them set specific goals.

"Homework shouldn't be a battle. It should be expected. It's as much a part of school as getting up and getting dressed each morning," says Anna Weselak, president of the National PTA.

Other dos and don'ts for parents, from the experts:

Show your children how school subjects are put to practical use, employing math to balance a checkbook, for example, or figure out a tip at a restaurant. Don't dis your own school experience. Instead of saying, "I hated math, too," in an effort to empathize, try something more encouraging, such as, "I had a difficult time too, and here's how I conquered it."

Regular communication between parents and teachers about expectations can keep everyone on the right path, she says. Be wary of children who report night after night that they have no homework.

On the other hand, if a child complains about way too much homework, or if it's taking far too long to complete it, it's fair for the parent to take up the issue with the teacher, Weselak says.

"Kids do need some free time and sleep time. They need physical activity and to eat dinner. It can be hard to fit it all in," she says.

Some parents are turning against the very idea of homework, saying it has become excessive and keeps kids from having fun, reading for pleasure, or pursuing other interests that will make them happier, more well-rounded people. Sara Bennett of Brooklyn, N.Y., is co-author of the book "The Case Against Homework: How Homework Is Hurting Our Children and What We Can Do About It" (Crown), due out this fall.

"Homework was interfering with my kids' intellectual development," she says. "To stop to practice spelling when your kid is reading a book is ridiculous."

Bavaria argues that good teachers can make homework meaningful by coming up with challenging, relevant assignments.

"Kids can see through busy work like Superman can see through steel," he says. "But relevant homework — kids will take that seriously."