LANCASTER, Pa. -- Angela Altrichter home-schooled all three of her sons through eighth grade.
But as her boys got older, Ms. Altrichter realized she didn't want to teach high school.
She looked for a program with a low student-to-teacher ratio and eventually chose 21st Century Cyber Charter School in Exton, Pa.
Ms. Altrichter's youngest son, Aaron, is now a junior at the school, where his schedule includes both live online lessons and independent assignments.
It's a good fit for Aaron, who hopes to pursue a career in the entertainment industry.
"[My teachers] are always very supportive," he said. "When we complete assignments, they give us very positive feedback."
The Altrichters, of Lancaster Township, are among a growing number of Pennsylvania families who are choosing cyber-charter schools.
Sixteen cyber-charters operate throughout the state, including four that opened just this fall. Another eight have applied to open next year, including one that plans a "cyber cafe" in Lancaster.
In 2011-12, the schools enrolled 32,322 students.
Cyber-charter schools are public schools. The Pennsylvania Department of Education grants the schools' charters and has financial and academic oversight. Families do not pay tuition. When a student within a school district's boundaries attends a cyber-charter school, the district foots the bill.
Cyber-charters are magnets for controversy, attracting defenders and detractors who are equally passionate.
Supporters say the schools offer choice and flexibility to families, who, for a variety of reasons, are dissatisfied by their experiences in traditional school districts.
Critics, on the other hand, say cyber-charters produce lackluster academic results, operate without sufficient oversight and put a financial strain on local districts.
Sharon Williams, head of school for Agora Cyber Charter School in Wayne, Pa., said despite cyber-charters' phenomenal recent growth, most people don't understand how the schools actually work.
"There's a perception that we don't know who these kids are," she said. "Not true."
There is no one typical cyber-charter school in Pennsylvania.
In 2011-12, enrollment ranged from 112 students at Central PA Digital Learning Foundation to 10,559 at The Pennsylvania Cyber Charter School.
Cyber-charters give students computers, printers and reimbursement for Internet service. Some provide other supplies, such as digital cameras and pedometers.
Some cyber-charters are connected to management companies or intermediate units (regional educational service agencies). Others operate independently.
All cyber-charters are governed by independent school boards. Many schools have satellite offices across the state to offer greater access to families.
The management companies, which provide computers, curriculum, textbooks and other services, are a source of controversy.
State Auditor General Jack Wagner, a vocal critic of charter school funding, has recommended limiting fees paid to management companies.
Schools' relationships with the companies "can result in excessive profit-making with public education dollars," he said.
But leaders of cyber-charter schools that use management companies said the relationship allows them to deliver quality online content.
Agora is part of a national network of schools affiliated with K12 Inc.
"I get the latest and greatest research," Ms. Williams said. "I have the opportunity to connect with other schools like ours. We share our challenges and best practices."
Emily Bailey, an eighth-grader at PA Cyber, wants to be a professional dancer. She practices for two to four hours nearly every day, ending as late as 9:15 p.m.
Attending a cyber-charter school gives Emily more time for both homework and dance practice.
"It's really flexible," said Emily, who lives in Lancaster County. "I love it."
Emily's schedule includes self-paced and live lessons. Her parents, Andy and Lena, leave much of the responsibility for schoolwork up to her.
"I don't think it's for every kid," Andy Bailey said. "You have to be disciplined."
The flexibility of online learning appeals to students like Emily, including actors, gymnasts, frequent travelers and those who work.
Cyber-charter schools allow students to work at their own pace. Many record live lessons so students can catch up at their convenience.
Online learning also appeals to former home-schoolers, gifted students, bullying victims or families unhappy with their home school district.
A high percentage of cyber-charter students -- typically 20 to 25 percent -- require special-education services.
Charter school teachers face less stringent requirements than those in traditional public school districts. All teachers in public school districts must be state-certified. Charter school law requires only 75 percent of teachers to be certified.
A new, more rigorous evaluation system for Pennsylvania public school teachers and principals is in development and expected to be in place by 2013-14.
Charter school teachers are not subject to the current 30-year-old evaluation system and would not be included in the new system.
No matter what their experience, cyber teachers must be comfortable with technology, Ms. Williams said.
Critics of cyber-charter schools question how teachers can truly connect with students when they rarely, if ever, meet face to face.
But cyber-charter school Achievement House's curriculum coordinator Victoria Asplen said online learning actually offers more opportunities for one-on-one interaction.
"You get to know your students much more quickly and much more deeply," she said.
Teachers typically are available beyond traditional school hours and use many forms of communication, cyber-charter leaders said.
21st Century student Aaron Altrichter said if he has a question, he visits a teacher's online "office."
Cyber-charter leaders say one of the biggest misconceptions is that their students are "loners."
Emily Bailey said she misses some of her friends but sees others in dance class. (PA Cyber reimburses families $100 a month for physical activity, which includes ballet classes, her parents said.)
Emily, who is taking high-school level French, is president of the French Club, which holds virtual meetings.
"Agora" means "gathering place." Building connections within the school community is a major key to student success, Ms. Williams said.
The school holds regular events, including ice-skating parties, prom and a statewide spirit day. Achievement House students can join a variety of clubs, including Students Against Drunk Driving, golf, gaming and Student Council.
Cyber-charter students also can find social opportunities by participating in activities in their home school districts, director of administrative services Jennifer Clarke said.
Angela Altrichter credited the local home-school organization and church youth groups for helping her family stay connected.
And, she said, "The one thing I like most about cyber school is that I get to see my kids all the time."