“Homework for young students should be short,” Duke University psychologist Harris Cooper said, and “lead to success without much struggle.” (Katherine Frey/The Washington Post)

I have attended 45 back-to-school nights over the past 40 years. They tend to follow a pattern. But this school year, I witnessed an exchange between a parent and a teacher like nothing I had seen before.

A father at the public elementary school in an affluent neighborhood asked: “Does a student have to do the homework?” The teacher said the assignments were important and should be completed.

The father didn’t give up. “Are students punished if they don’t do them?” he asked. The teacher paused. It sounded as if she, too, hadn’t heard that one before. She shrugged and said there would be no punishment. That may not be entirely true, but that is what she said.

I admired the father’s audacity. Some parents wonder about this but don’t dare raise the question in a room full of other parents. Since homework is experienced by nearly everyone, it gets much attention. The latest comes from the Center for American Progress, in an unusual report based on an online survey, “Homework and Higher Standards.” The report from the liberal think tank buttresses the pro-homework argument but suggests to me (usually a homework fan) an adjustment that might please that dad.

The center collected a great deal of data, including a survey of 372 parents from throughout the country using an online tool that lets the parents submit homework samples. The survey group was whiter and younger than the U.S. population and represented mostly parents with elementary school students.

Some of its more interesting conclusions:

●Homework samples submitted by the parents were mostly aligned with the Common Core State Standards, used in 41 states and the District.

●More than half of the elementary school parents said the assignments they submitted were too easy for their children.

Does that mean we need tougher homework in elementary school? Not necessarily. Research shows that homework through fifth grade has little impact on achievement, compared with homework in middle and high school.

After looking at more than 100 studies, the scholarly guru on this issue, Duke University psychologist Harris Cooper, concluded in 1989 that “for elementary school students, the effect of homework on achievement is trivial, if it exists at all.” In 2006, after reviewing more rigorous studies, he stepped back a bit and simply concluded the causal effect of homework on achievement was much stronger in grades seven through 12.

“Homework for young students should be short,” he said, and “lead to success without much struggle.” The simple homework described by the Center for American Progress study suggests many schools are following that advice.

If that’s the case, why not let parents such as that father at back-to-school night decide if younger kids are going to do homework at all? I have suggested that elementary school homework be limited to free reading. Use the old 10-minute rule: 10 minutes times the grade level each evening, which is 40 minutes of reading for fourth grade, 50 minutes for fifth grade and so on. Some schools do this already.

I suspect parents who worry about too much homework already encourage their children to read. So why not let them decide if other overnight assignments through fifth grade are worth doing?

The school could require the parents to submit a statement of at least 200 words on why they want to control homework. Post all the statements on the school website, without names, so everyone knows what is going on. See what happens.

Parents who think of school as more of a track meet than a learning experience will object that this puts their child at a disadvantage in grading. Fine. They can stick with homework.

The authors of the Center for American Progress study were Ulrich Boser, Meg Benner and John Smithson. They recommended district policymakers and principals regularly review homework assignments for quality.

They are not radicals. They do not accept my view that parents should be allowed to excuse their children from homework in the lower grades. I am not saying a fourth-grader shouldn’t do her homework if she wants to. If the child likes the assignment, go for it.

But I think kids that age can often tell which exercises are worthless. They frequently will have a good idea of something better to do.