When Barbara Andrews got a letter from Strasburg Rail Road last month, she figured it was a typical invitation for her students to visit the tourist attraction.

Andrews, principal of Martin Elementary School, was right, but the invite had an appealing catch: The students and their adult chaperones could ride the rails for free.

Andrews jumped at the opportunity, booking field trips for students in kindergarten and second grade for April 25 and 26.

"We've never, ever had that opportunity before because the cost was too high," she said of the field trips. "It's a free trip."

The promotion, announced in February, is designed to get more student groups to visit the railroad, which has seen a decline in public-school field trips in recent years amid the souring economy.

Operators of other attractions and historic sites in Lancaster County say they, too, have seen their numbers decline.

In response, they've tweaked their programs and discounted their fees to try to increase business.

Lancaster Science Factory is offering free admission to groups of sixth-graders who visit the Lancaster city attraction, but the promotion by Strasburg Rail Road is even more comprehensive.

The railroad, which operates historic trains pulled by steam locomotives, is offering free fares for up to 102 students and adult chaperones on field trips from public elementary schools.

Additional passengers will be charged $12.50 per ticket.

The free tickets are limited to off-peak midweek hours and are available on a first-come, first-served basis, with a maximum of 180 riders per train. Only one adult for every five students qualifies for a free ride.

The regular group rate is $6.50 per person, so the discount is significant.

"All we have to come up with is the funds for the bus," said Andrews, who estimates that will cost her school about $175 for each group of students.

The railroad also is allowing school parent-teacher organizations to host fundraisers on its grounds during several weekends from April through October.

Ten percent to 15 percent of ticket sales on those days will be donated to the schools' PTOs, and the groups will be allowed to sell school merchandise on site.

The promotions are part of the railroad's community outreach efforts, said spokeswoman Tiffany Dodson.

They're also being offered "to address the concern that field trips and extracurriculars are being cut at schools, and students are not getting the extra enrichment" such activities provide, she said in an email.

The number of field trips to the Strasburg attraction has dropped noticeably in recent years, said Dodson, who did not have figures to quantify the drop.

"We would definitely pin the decline on the economy and cuts in school funding," she said. "It's certainly been more of a decline in the public schools than in the private schools."

Hands-on House children's museum also has experienced a drop in school visitors in recent years, said Lynn Morrison, executive director.

"It's a challenging time for school budgets," she said. "The big difference we're seeing is that we have more programs that we bring to the schools. We go to them; they don't come to us."

The museum has expanded its Discovery to Go program, which eliminates transportation costs for schools.

The downside, Morrison said, is that students don't get a traditional field trip experience at a key time in their young lives.

"We're often a child's first field trip," she said. "They learn how to work together as a group, and they learn to represent the school."

Rock Ford Plantation also has seen a decline in public-school field trips, said Sam Slaymaker, executive director.

"What we find now is we have fewer public schools but more home-school groups," he said.

The number of student visitors has been shrinking over the past decade, he said, as schools have shifted their academic focus away from history and more toward math and reading.

"There's been a declining emphasis on history because it often isn't reflected in test scores," Slaymaker said.

The decline has leveled off in recent years, he said.

Nonetheless, the Colonial-era estate currently is running print ads that, for the first time, specifically target school groups.

North Museum of Natural History & Science has implemented several promotions aimed at getting more students through its doors.

Earlier this year, it offered schools a free planetarium show in addition to the regular museum program if they booked spring field trips before the end of February, said Margie Marino, museum executive director.

That effort yielded 27 bookings by groups ranging from 20 to 130 students, she said.

Last year, North Museum implemented Science Around the Corner, which targeted elementary schools within walking distance of the city museum.

Schools paid a flat fee of $550 to cover admissions for as many students as the school wanted to send from August through January.

Last year, eight schools took advantage of the promotion, which was expanded this year to all county elementary schools. But Marino said only two or three signed up for 2011-2012.

"This year it's been a little tough," she said. "That $550 seems insurmountable for some schools."

More visitors means more revenue for the museum, which is struggling with the same kind of cuts in state and federal aid afflicting public schools.

"It costs me just as much to run the museum whether there are 50 people in here or 300, so we try to get as many people in here as we can," Marino said.

Officials at other attractions, including Lancaster Science Factory, Cherry Crest Adventure Farm and Hans Herr House, said they have not implemented new promotions specifically targeting school groups.

Bob Herbert, Science Factory director, said the technology and science center has been careful not to raise its group-rate price — $5 a head — and has been more aggressive in bringing in new displays.

"We just have to be more creative in getting kids in here," he said.

With its free-ticket promotion, Strasburg Rail Road stands to lose out on potential revenue, but Dodson said the trade-off is worth it.

Picking off-peak time slots when the trains have unused capacity "made it easy to incorporate the field trip concept into the business model," she said in an email.

The promotion will enable more children to learn about "the role steam railroading played in the history of our country and ensure that quality, educational field trips still exist for our children," Dodson said.

Whatever the reason, Andrews is glad the promotion is being offered. Without it, her students — many of whom have never ridden a train — wouldn't be able to go.

The field trip will mesh nicely with an academic unit on Lancaster County history that Martin second-graders are studying, she said.

"That railroad is fabulous, and every child loves trains," she said. "Who doesn't stand in awe of a steam engine?"

bwallace@lnpnews.com