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Do you review your daughter’s homework every night? Robinson and Harris’s data, published in The Broken Compass: Parental Involvement With Children’s Education, show that this won’t help her score higher on standardized tests. Once kids enter middle school, parental help with homework can actually bring test scores down, an effect Robinson says could be caused by the fact that many parents may have forgotten, or never truly understood, the material their children learn in school.

Similarly, students whose parents frequently meet with teachers and principals don’t seem to improve faster than academically comparable peers whose parents are less present at school. Other essentially useless parenting interventions: observing a kid’s class; helping a teenager choose high-school courses; and, especially, disciplinary measures such as punishing kids for getting bad grades or instituting strict rules about when and how homework gets done. This kind of meddling could leave children more anxious than enthusiastic about school, Robinson speculates. “Ask them ‘Do you want to see me volunteering more? Going to school social functions? Is it helpful if I help you with homework?’ ” he told me. “We think about informing parents and schools what they need to do, but too often we leave the child out of the conversation.”

One of the reasons parental involvement in schools has become dogma is that the government actively incentivizes it. Since the late 1960s, the federal government has spent hundreds of millions of dollars on programs that seek to engage parents—especially low-income parents—with their children’s schools. In 2001, No Child Left Behind required schools to establish parent committees and communicate with parents in their native languages. The theory was that more active and invested mothers and fathers could help close the test-score gap between middle-class and poor students. Yet until the new study, nobody had used the available data to test the assumption that close relationships between parents and schools improve student achievement.

While Robinson and Harris largely disproved that assumption, they did find a handful of habits that make a difference, such as reading aloud to young kids (fewer than half of whom are read to daily) and talking with teenagers about college plans. But these interventions don’t take place at school or in the presence of teachers, where policy makers exert the most influence—they take place at home.

What’s more, although conventional wisdom holds that poor children do badly in school because their parents don’t care about education, the opposite is true. Across race, class, and education level, the vast majority of American parents report that they speak with their kids about the importance of good grades and hope that they will attend college. Asian American kids may perform inordinately well on tests, for example, but their parents are not much more involved at school than Hispanic parents are—not surprising, given that both groups experience language barriers. So why are some parents more effective at helping their children translate these shared values into achievement?