Jeri Jones, 5 years old and already contemplating the larger issues of life, decided that it was her part to explain one of the fundamentals of the Christian faith to her friends in Largo on Friday morning:

"Jesus paid for our sins when he died on the cross," she said. "And Jesus rose from the de-, um, . . . from the desert."

Over in Upper Marlboro, some other children were trying to figure out who wrote the four Gospels. Said one 7-year-old with absolute assurance: "Matthew, Mark, Andrew and Mike."

Well, both answers were not quite right. What happened to Luke and John? And Jesus rose from the dead, not the desert, but both were close enough to put big smiles on the faces of teachers at vacation Bible schools, where it doesn't always matter if the answers are just right, as long as children are learning and talking about God--and having a good time, too.

Part summer camp, choir practice, art class, prayer time and day care, VBSs, as they are called by devotees, are increasingly popular across Prince George's County.

Summertime comes, and the VBS signs go up in every town and outside churches of every denomination.

Most are one- or two-week programs that focus on exposing children to "Christ's truths," organizers said.

And this summer, enrollment is up, according to some teachers who have a long history of involvement with vacation Bible schools. More aggressive advertising and a need for day care matched with a national trend--the return to spirituality--are fueling the growth of the summer programs, VBS officials said.

"Most definitely, I'm noticing a rise in popularity," said Terrie Matthews-Whiting, a paramedic who taught religion at Divine Peace Lutheran VBS in Largo last week. "It gets bigger all the time."

At Divine Peace, the big jump in enrollment came last year--doubling from 50 students to 100. This year the enrollment in the one-week session is about 100.

Most programs are free and open to all families, including non-church members. It is a time for reflection and fun for the VBS-goers who already know their Bible. It is a time for exploration and exposure for children who might not already be familiar with the Bible basics of Christianity. And for some, it is a time to save on child care while getting multiple doses of religious education throughout the summer.

"It's really to increase knowledge, and if we can, save souls, too," said Mandaline Gilliam, director of Mount Ephraim Baptist Church VBS, which last week had about 64 students ages 3 to 12. That is about 15 more students than last year.

"And it's for recreation, because a lot of times in the summer, children are bored and they're looking for something to do."

It's a form of summertime outreach--you could call it minor missionary work--that the recruiters seem to enjoy as much as those recruited.

"It's very rewarding just to talk about God with kids," Gilliam said.

Cora Phillips, who teaches kindergarten at Divine Peace Lutheran VBS in Largo, said, "My main job here on Earth is to get children to understand Jesus. I don't see any purpose in anything else."

But that doesn't mean it's easy.

"Basically, you have to teach through song and colorful presentation," said Peggy Parker, a real estate assessor teaching at Bible school for her 20th summer. Last week, she taught first- through third-graders at Union United Methodist Church in Upper Marlboro. "It's difficult making them understand that everything isn't tangible."

Try explaining to a 5-year-old the difference between "God" and "Jesus" and the "Holy Spirit," while maintaining that they are "one God in three persons."

No wonder Jeri Jones, one of Phillips's students (and also her granddaughter), takes her lessons so seriously. When she talks about the mother of God, "Mary" comes out sounding like "May-wee." No matter. Jeri knows who she's talking about.

"There's two May-wees outside where Jesus was" laid to rest, she said, clarifying a common oversight pertaining to the resurrection. "Two different May-wees."

The lessons vary in approach from one VBS to another, but for the most part, the teachers, many of whom are regulars, start with Jesus's life as a teacher and healer and end with the resurrection. And they all have one thing in common: The lessons are taught in a traditional way without high-tech or comic-book embellishments.

"I honestly believe God lets children understand even what's difficult for adults," Phillips said.

The lessons are craft-oriented and usually last a half-day, with plenty of time for play scheduled in between instruction.

And here's how the children feel: "I come here because it's a lot of fun," said Savannah Frazier, 12, of Upper Marlboro, who studied at the Mount Ephraim Baptist Church VBS. "You don't have to just sit down and listen. You learn about Jesus and faith, and you're having fun at the same time."

Said Mildred Bowman, 10, of the same school: "This keeps me out of trouble and gives me something good to do. . . . I'd probably be at home running around doing all the things my grandmother says not to do."

For some families, it's really just a form of day care, but teachers aren't bothered.

"No matter," said Jon Roux, a VBS teacher and the principal at Divine Peace Lutheran. "Our mission is to tell people about Christ. It's a wonderful outreach into the community."

Some children go from one Bible school to another all summer, with parents scrambling to find churches that offer classes at times and dates that don't conflict.

"When they call to register," Roux said, "they're looking to fill specific time slots."

Sarah McDowell, 11, is in her fourth year of VBS at Divine Peace and plans to hit a few more week-long classes before the summer is over.

"I came the first time when I was 7 and thought, 'Okay, that's it. I'm coming every year,' " she said.

A tradition that goes back generations, VBS also is changing with the times. A few churches have begun offering adult and night classes.

"The tradition never died off," Matthews-Whiting said. "It just got better."

CAPTION: Hugh Carr, with a sticker on his hand, puts a sticker in a workbook at Divine Peace Lutheran.

CAPTION: At left, April Halmon reads the Bible during a lesson with the sixth-grade class at Divine Peace Lutheran Church's vacation Bible school. Below, the Rev. John Mittelstaedt, pastor of Divine Peace in Largo, points Janai Greenhill in the right direction as children line up after playtime last week.

CAPTION: Malik Matthews smiles at Bible school at Divine Peace Lutheran Church. The church's Bible school enrollment doubled last year.