Florence Atkins, parent of a first-grader at Connections, a Big Island charter school, said it's easy to see why charters are gaining in popularity.

"It's the teacher-to-student ratio. It's the environment. You have teachers there that actually want to be there, that want to teach. It's a much more positive environment and much more challenging than any public school," she said.

But advocates say charter schools already don't receive the money they're due, and wonder how they would handle half again as many students without funding for facilities and a lifting of the cap on new charter schools.

Connections grew by 21 students this year but had to turn away many more applicants. The wait list is more than 100 students long.

Principal John Thatcher said the list is so long, "I could probably open another school. It's really sad. I really hate to turn people away, but we don't have the space."

Jim Shon, executive director of the Charter School Administrative Office, suggests the projected enrollment gains indicate growing credibility and popularity among the schools, which are part of the Department of Education, but have more flexibility in governance. The majority of the charter schools are now in their fourth year of operation.

The 27 charter schools have long argued they need more money, and advocates will rally at the state Capitol and other areas around the state at 11 a.m. today to send lawmakers the message that the schools deserve at least as much as the law dictates for charter schools.

Right now, both the House and Senate versions of the state budget are $7 million to $9 million short of what charter schools would receive according to the budget formula, Shon said.

"That's part of the concern at the rally," Shon said. Uncertainty about funding makes it difficult for charters to plan for next year, he said.

The charters also worry that any growth in enrollment will lead to significant budget deficits, since even if every charter school statewide increased by only four students, $650,000 would need to be added to the budget, Shon said.

Charters say there is clear demand for increased enrollment.

At Halau Ku Mana, a Hawaiian-based charter school in Manoa, community demand will lead to a small expansion next year, although not significant enough to compromise the integrity and values of the school.

Innovations, a Big Island charter school, will not be able to expand beyond 120 students to maintain its small class sizes, but has seen its wait list triple to 150 since last year.

"We have more people on our wait list than we have in our school," said principal Barbara Woerner.

With every student returning next year, the school has only 24 openings for fall, which to Woerner indicates a need to lift the cap for new charter schools.

"There's a real need, a real interest from parents who want something different," she said.

Kanani Leanio, a parent of two children, one each at Innovations and West Hawai'i Explorations Academy charter schools — both on the Big Island — said moving her kids there has made a world of difference.

Three years ago, her older son, then 8, didn't want to go to school anymore. "I needed to find another alternative to help him," she said.

Innovations, and now West Hawai'i Explorations Academy, have proved to be the right alternative. "Now I have to pay him to stay home from school when he's sick," she said.

Leanio thinks charters appeal to parents because many have small class sizes and more hands-on learning opportunities. The intimate learning environments allow students to discover their strengths and gain in confidence, she said.

Atkins, the Big Island parent whose daughter has been at Connections for two years, suggests that charter schools are growing in popularity by default. "There's a growing disgust with the public school system," she said.

The study released Wednesday shows that about 90 percent of charter school students would otherwise attend traditional DOE schools, in part because of financial constraints and on the Neighbor Islands because of a lack of private school alternatives.

Atkins said finances played a part in the decision to go charter, but added, "Even in private schools, we believe she would be losing out on a lot of social skills."