ARLINGTON, Va. (AP) — A crowd of children was already waiting by the curb one day this month when a yellow school bus stocked with books pulled up in front of their high rise apartment in South Arlington. The doors opened, and within minutes a team of teachers set up a card table, powered up their laptops and plugged in electric scanners.

Presto. A portable library.

Abingdon Elementary School's "Read and Roll Book Bus" is the latest attempt to address an annual concern for educators — a summer slide in reading skills.

The drop in reading levels tends to fall along class lines, with students from poor families losing ground while those from middle-class backgrounds make slight gains. The losses accumulate, so that by ninth grade, two thirds of the achievement gap in reading between poor kids and their peers can be attributed to the school-free summer months, said Gary Huggins, chief executive of the Baltimore-based National Summer Learning Association.

Bridging the gap begins by making sure that all students have access to books, researchers have found. Children in lower-income families are less likely to amass personal book collections, and public libraries aren't a reliable option if students don't have reliable transportation.

Abingdon reading specialists Susanna Smith and Mary Lou Rubé learned about the research at a reading conference last spring, as well as a possible solution: Bring the books to the students.

Principal Joanne Uyeda jumped on the idea, and lined up a weekly school bus and driver. "Then things started rolling," Smith said.

The bus got a makeover with the addition of shelves and carts that teachers filled with about 2,000 donated books. Volunteers helped upload the titles into a computerized system.

They set up a bus schedule with four weekly stops and even got a soundtrack for their roving library. When the bus pulls up, students are treated to a bookish version of a Black Eyed Peas Song. "I've got a feeling...that this book's gonna be a good book" the chorus repeats, like an ice cream truck jingle.

At the first stop one Thursday this month, Seynabou Anne, 6, was waiting with her mother and three books in hand, including "Miss Bindergarten Gets Ready for Kindergarten," ''Clifford the Big Red Dog," and a book about two rabbits named Max and Ruby.

Her mother, Kama Diawara, works as a security guard in an office building and said it's hard to make it to the public library. But she has tried to bring her daughter to the mobile library each week.

When Seynabou went to return her book, her kindergarten reading teacher was there to ask questions. "Which character did you like better? Max or Ruby?," she asked.

"I like Ruby, because she's nice to her brother," said the rising first grader.

At last half a dozen teachers have volunteered each week, helping the students pick titles that highlight their reading levels, checking their comprehension, and encouraging them. One teacher brought a cooler full of ice pops every week.

Parents also got involved, starting at a family library night last spring, where the teachers gave a presentation about the importance of summer reading and announced the bus schedule for the mobile library.

The book drive is only one of Abingdon's literacy programs. The school also participates in a "summer mailbox" program, in which about 600 students countywide have books mailed to them over the summer. Students get to pick out titles that interest them in advance. The program has proved successful in staving off reading loss, a result that has been mirrored in other, larger-scale programs that give students books over the summer.

Smith said that the school plans to monitor the reading levels of the 200 students who participated in the mobile library this summer so educators can measure the effectiveness of the five-week program.

The library's second stop Thursday was a corner in a residential neighborhood, surrounded by shady trees. Norma Machado, 6, was among the children who came to meet the bus.

Her mother, Martha Machado, said Norma likes to read, but she prefers to be read to. And she is more likely to draw a picture or play outside than to pick up a book on her own.

"A lot of times, I say, 'Please, Norma, read,' " she said. The bus is fun, though, a place she likes to visit to see teachers and get new books.

"It's been good motivation," Martha Machado said.