Clustered around desks pulled up in groups of six, the fifth-grade students stared intently at the thin picture book, with its cheerful cartoons of skipping animals.

"Un hipopotamo se subio al autobus," they chanted together with enthusiasm. Turning the page, they continued. "Un chivo se subio al autobus."

A hippopotamus got on the bus. A little goat got on the bus.

The students studying the Spanish easy reader last week were at Frances Hazel Reid Elementary School in Leesburg. But they could just as well have been in Sterling or Purcellville or South Riding.

Five years after Loudoun County introduced Spanish instruction for elementary school students, the goal of teaching the language to every child in first through fifth grades at all 44 elementary schools has been achieved.

What began as a tiny pilot program to offer one lesson each week to students in kindergarten and first grade at just 10 schools has grown into a major county commitment. And this year, after several years of focusing on listening and speaking skills, fifth-graders are being introduced to reading in Spanish, in the form of such simple books as "Un Paseo en Autobus" ("A Ride on the Bus.")

It is a novel approach: Loudoun's school system is the only one in Virginia to introduce a foreign language in all of its elementary schools.

Other school districts, including Fairfax County's, have pursued language-immersion classes in select elementary schools, aiming to help a few students, chosen by lottery, become bilingual. But Loudoun officials have decided that, given the region's exploding population of Spanish speakers, every child deserves a chance to become comfortable with the language. The county's program includes special education students and immigrant children still learning English, students who tend to be excluded elsewhere, said Suzette Wyhs, the school system's foreign language supervisor.

"We want to prepare kids for the future," she said. As Spanish gains prominence in the United States, Wyhs said, more Americans will need to learn it "in order to be able to run a business or work in any kind of field."

The goal isn't so much fluency as it is introducing foreign words to young ears early, so that when they hear a new language in a more formal setting later, it won't sound so foreign. Students in first and second grades have 30 minutes a week of the Foreign Language in Elementary School (FLES) program. Third- through fifth-graders have two lessons a week, each 30 minutes.

The introduction of reading is an important step -- a sign that the program is maturing, Wyhs said. She said teachers use the same methods to teach Spanish literacy in fifth grade that they use to teach first-graders to read English. In future years, students will be introduced to Spanish reading even earlier.

"We could discover they leave fifth-grade reading at a second-grade level -- in Spanish," she said. "That would be huge."

The universality of the program has been one of its major selling points to parents. Before FLES was expanded to every elementary school, parents lobbied to have their schools chosen. And school officials have promised that as new schools open, new FLES classrooms will open as well.

That's a commitment that school officials in neighboring Fairfax have been looking at with interest. Paula Patrick, Fairfax's foreign language coordinator, said she is impressed with Loudoun's inclusive program. In Fairfax, only 26 of 136 elementary schools offer some form of foreign language instruction.

There's interest in expanding programs, Patrick said, but offering language instruction to all of the district's elementary schools would require massive funding. (Loudoun's program has cost about $2.5 million so far.) Patrick also said she is not sure whether Fairfax parents would want only one language offered.

In Loudoun, the decision to offer only Spanish has had its critics. School Board member Bob Ohneiser (Broad Run) has argued that students might feel obligated to take Spanish when they reach the eighth grade, instead of also considering French, German or Latin.

Wyhs said school officials will be curious to see whether the number of students who choose Spanish over other languages rises. She maintains that offering a little Spanish early will help students learn any language more easily.

FLES recruits many of its teachers from the North Carolina-based Visiting International Faculty Program, meaning many students are taught by a native Spanish speaker. Because of this, students come away learning more than just the language, said Alix Gil, the FLES teacher at Reid Elementary.

Gil is on loan to Loudoun schools for three years from her native Colombia, where she was teaching English to elementary school students.

Until they met her, Gil said, many of her students had never heard of Colombia. Now they can find the country on the map and talk about its culture.

Gil said she also tells the children about the differences between Reid Elementary and her school in Colombia. For one thing, her Colombian students had 10 hours a week of foreign language instruction.

But Gil said certain things are the same in both countries. By using voice inflections, pictures and hand motions, she can carry on a lesson entirely in Spanish here -- or in English there -- even with students who do not speak the language. They understand context and, in time, more and more words.

Another similarity, she said, is the importance of keeping a lesson enjoyable.

Teachers say that in the low-stress environment of FLES -- there are no tests or homework -- students on the edge of adolescence are willing to do things they enjoyed when they were younger, such as singing, playing games and reading picture books.

"If you tried getting the kids to do some of these things in English, you'd have a revolt," said Faith Laughlin, a FLES teacher at Round Hill Elementary School who helped develop the curriculum. "They'd feel like you're talking down to them. But they never see it that way here."

Alix Gil, who teaches Spanish at Frances Hazel Reid Elementary, comes from Colombia, where she teaches English to elementary school students.