For almost 30 years Ligaya Ricafrente moved up the success ladder at Servco Pacific, all the way from clerk to vice president. But the minute she retired in 1992, she knew she'd made a mistake.

"I was climbing the walls," Ricafrente said recently, standing in a shady courtyard at Campbell High School in 'Ewa Beach, where she's one of the district's outstanding bilingual teachers for immigrant students learning English.

Ricafrente had started her professional career as a teacher years ago in the Philippines. And then, in 1992, she went back to the classroom.

"The knowledge I got from Servco was my torch to give inspiration for children to succeed," she said. "But the most important thing I impart is the value of learning."

Ricafrente is no longer a rare breed in the teaching ranks. Increasingly, people are choosing to leave professions in midcareer, or even upon retirement, to become full-time or substitute teachers. There are many reasons — including the desire to serve, leave the hurly-burly corporate world behind, work in their own community or simply try something new.

While the practice is bringing in a relatively small number of teachers, it is helping Hawai'i's teacher shortage, plus bringing new blood and new ideas into the school setting.

And with President Bush promising to encourage 30,000 mathematicians and scientists from the business world to step into America's classrooms, the idea of career switching is gaining even wider recognition.

Not every school can point to the number of career shifters Campbell has landed, and there are no firm statistics on how many are coming into Hawai'i's teaching ranks, but often they show up in the system as emergency hires who go on to obtain teaching credentials.

"I think it's a trend and an increasing trend, based on the factors (that) there aren't enough well-prepared teachers and the accountability standards (are) higher under No Child Left Behind," said Tom Barlow, chief executive officer of Pacific Resources for Education and Learning. PREL is an educational think tank offering resources, support and information for schools in Hawai'i and the Pacific.

"The whole issue of highly qualified teachers being one criteria of No Child Left Behind is really driving this."

On most school days, Leonard Wong stands a few yards from Ricafrente in a Campbell High courtyard, keeping a watchful eye on the ninth-graders who swarm out of class for lunch. After a career in law enforcement in Los Angeles, and official retirement, Wong stepped into a new job as security officer for the school.

When he was lured by a brother to retire to Hawai'i, Wong decided to try substitute teaching to boost his income. But it wasn't long before Campbell High School principal Gail Awakuni persuaded him to take the full-time security position.

"I wouldn't want a permanent position," he maintains, shading his eyes against the sun. "But I'm going to find out what it's all about."

At Campbell, Awakuni is a tireless recruiter for her teaching staff. She has to be. With one of the biggest high schools in the state, finding and keeping teachers is a major challenge, especially in a state that's short as many as 400 to 500 teachers every year. But she's finding that people seeking midcareer change, as well as the population bulge from subdivisions springing up throughout the Leeward O'ahu area, provide some of her best prospects.

"I've hired three teachers this year, because they live in our area and are making career switches," she said. "They're leaving private enterprise and coming into this profession. They come with the added value of other kinds of experiences.

"And the new subdivisions are working to our benefit," said Awakuni. "They look at the traffic and that may be a consideration. It's always good to hire from the community, because they have a vested interest."

At the University of Hawai'i, Virgie Chattergy has been overseeing the Transitions to Teaching program, a financial incentive program that pays tuition to encourage people from all walks of life to come into teaching and get their credentials while they teach.

"It's intended to help people who want to get into a career teaching math or science," said Chattergy. "It's specifically geared to math and science academic majors, but it also includes graduates with a B.A."

Since 2002, when the grant that finances the program began, UH has trained 86 new teachers under this incentive program, with people switching from such careers as medicine, engineering and technology to head into teaching.

"Times are changing," said Chattergy. "A lot of people have tried a job and didn't like it and then are coming into the College of Education. We have our share of nontraditional students."

Melissa Goo is one. A former medical assistant and then manager of Hawai'i Pacific University's science laboratory, Goo switched careers in her mid-30s to become a classroom science teacher. Now in her fourth year of teaching, she says it's the toughest job she could imagine — she's e-mailing parents in the middle of the night sometimes to alert them to issues — but nonetheless is happy she switched professions.

"I had two reasons why I left to go into teaching," said Goo. "One was that I have a son with a learning disability in the public school system, and I'm a firm believer if you're not part of the solution, you're part of the problem. So rather than complaining, I decided to go head-first in to see how I could help him.

"Secondly, I wanted to do something more direct to prepare students to come into college. What I saw in the college system was the vast majority of students coming in unprepared for the work. Based on my conversations with professors, we all seemed concerned about why students were coming to us like this. So I decided to find out what was going on."

As an emergency hire at Mililani Middle School for her first two years, Goo was particularly concerned about educating parents about what goes on in the classroom and how their children are progressing. That's the kinds of thing she wanted to know as a parent.

"I found that the parents appreciate whatever information they get from teachers about what's going on," she said. "They really crave information. So I send a lot of e-mail. That's the most efficient method of communication because there are no time constraints."

If a child is having trouble of any sort, Goo shoots off an e-mail with a heads-up.

"I almost always get a response within 24 hours," she said. "They'll say thanks for the e-mail. We'll get on it."

Now teaching science at Moanalua High School, having been "bumped" from Mililani by a more senior teacher, Goo gained her credentials in 16 months and is going to sign up shortly for a two-summers master's program. But she already finds she's able to bring her real-world experience into the classroom.

"There are no words to describe how hard and difficult doing this job is," said Goo. "I couldn't have done it out of college. My maturity and my experiences are what I draw on. I would not have had the maturity or the experience to do it well."

Carsten D. Vogel also has switched gears and is heading toward teaching instead of the law career he'd been planning.

Even though he finished three long years of law school, the 28-year-old has decided it's not what he wants anymore.

"I was all geared up to be a lawyer," he said. "I was actually on the fence about whether I was going to take the bar exam and go into the whole mode of working my tail off for the next five years when I decided that wasn't for me."

With a bachelor's degree in science, Vogel is now planning more school to get a master's degree to teach science.

"I decided law wasn't going to be rewarding like I think teaching will be," he said. "It keeps you young.

"I want to be a science teacher, and I want to still be jumping in streams catching crayfish when I'm 50."