Languid summer days are near at hand. For students finishing the traditional academic year, time — free and fallow — beckons. But as days slip into weeks and months, something else accrues alongside rest and refreshment: a skills drop-off that erodes learning gains.

Low-income students are most at risk. Unlike their more affluent peers, they lack widespread summertime access to books or enrichment. This summer inequity explains much of the income-based achievement gap, research shows. But any student can fall behind if summer becomes a wasteland of mindless entertainment or unstructured indolence.

How can students forestall the summer slide? Read. Repeat.

Reading for fun, and often, has significant, sustained, and positive impacts on achievement. No epiphany, this still bears repeating. On the most recent National Assessment of Educational Progress in 2015, just 34 percent of eighth-graders and 36 percent of fourth-graders scored at or above proficient levels in reading. Eighth-grade scores have declined since 2013; fourth-grade scores have flatlined.

There’s no sign of a reading revival. Reading for fun has declined among kids of all ages since 2010. That’s according to Scholastic’s 2017 “Kids and Family Reading Report,” a biannual survey of more than 2,700 parents and children.

What promotes reading? Access to books. In Scholastic’s survey, frequent readers had far more books at home than infrequent readers (141 books, on average, compared to 65 books). Trends hold true across cultures and continents. Research by M.D. R. Evans and colleagues, published in 2014 in the journal “Social Forces,” found greater family book ownership was linked with higher scores on an international reading test for 15-year-olds in 42 countries.

How can schools foster book ownership and summer reading? Literacy expert Richard Allington’s seminal research, published in Reading Psychology, found that giving low-income students 12 self-selected books at an end-of-year book fair was as effective as summer school in boosting reading performance. It’s also much less expensive.

WAKE Up and Read, a community collaborative launched in 2012, builds on research — targeting summer learning loss at high-need schools through a partnership with Wake County Public Schools. Now and through the end of June, WAKE Up and Read is giving away 112,427 community-donated books to children at 10 elementary schools (as well as at childcare and community centers), according to Jane Small, the group’s Summer Learning Action Team co-chair.  “Each student gets to select 10 books to keep forever. In total, we will provide books to more than 7,000 students in Wake County,” says Small.

Parents also might want to dust off that library card. A 2015 Library of Virginia study found that rising fourth-, fifth-, and sixth-graders who participated in summer reading programs performed better than non-participants on state reading tests, even two years after participation.

What else? Evidence points to reading at least five books. Adult guidance and encouragement are critical, but kids should choose books themselves. Some choices might make literature mavens cringe. The children Allington studied preferred books about pop culture or series such as “Captain Underpants.”

Of course, choices vary based on age, interests, and gender. Boys, who trail girls in pleasure reading, are hooked by science fiction, sports, fantasy, war — even topics adults might find silly or a bit revolting. One American Library Association boys’ reading list proclaims, “Reach your reluctant readers with bodily functions and blood and guts.” A confession: I laughed my way through it.

Classics have their well-earned place, but summer books need not be by Dante or Dickens to school the mind. What must they be? Accessible. Enjoyed. And read — again and again.

Kristen Blair is a Chapel Hill-based education writer.