Teach for America's program in Philadelphia has received a major boost to increase the number of top college graduates it sends to city schools.

The Lenfest Foundation announced a challenge grant yesterday of at least $10 million to expand Teach for America's presence in Philadelphia over 10 years, starting in fall 2009.

It is the largest grant offer a regional Teach for America program has ever received, said a spokesman at the group's headquarters in New York.

"We're thrilled," said Mike Wang, executive director of the program in Philadelphia. "What this will do is give us some additional incentive and lay the foundation to recruit, train, and provide ongoing support for a minimum of 300 teachers in Philadelphia each year."

Under the terms of the Lenfest Foundation grant, $1 million will be disbursed each year to the program in Philadelphia, provided the program sends at least 300 instructors to city schools and raises $1 million from other private sources.

The Lenfest Foundation hopes the grant will spur other foundations, corporations and individuals to support the program.

"Teach for America is about changing the lives of children growing up in Philadelphia for the better," H.F. "Gerry" Lenfest, chairman of the foundation, said in a statement. "I can't think of a better investment in our future." Lenfest, a well-known philanthropist, founded Suburban Cable.

Founded in 1990, Teach for America aims to narrow the achievement gap between students at high-poverty and affluent schools by sending top college graduates to teach in classrooms in low-income areas that have difficulty attracting qualified teachers.

The participants, called "corps members," pledge to teach for at least two years. While they are with the program, they are trained by Teach for America and take additional courses to become certified teachers.

The program has been sending instructors to help fill vacancies in Philadelphia's most difficult schools since 2003. There are 268 corps members in city classrooms this academic year.

Fernando Gallard, a district spokesman, said Teach for America was an important component of the district's recruitment efforts.

"They do bring a tremendous amount of energy and focus," he said. "That is what we look for in every teacher we hire."

Bruce Melgary, executive director of the Lenfest Foundation in West Conshohocken, said the foundation had been one of the program's staunchest backers in Philadelphia.

"This foundation has supported Teach for America in Philadelphia through multi-year grants," he said.

By May 2008, he said, the foundation will have given the program $3.9 million.

The new grant has been structured to help the regional office meet its goal of expanding to 400 corps members.

The foundation has pledged to increase the amount of its grant from $1 million to $1.5 million in any year the program places 400 instructors in city schools.

Therefore, Melgary said, it's possible the grant could total $15 million.

Although the program helps the district fill vacancies, some students have complained that the two-year stints lead to instability at troubled schools that already have high teacher turnover.

The day before the grant was announced, members of the Philadelphia Student Union urged the Philadelphia School Reform Commission to put incentives in the new teachers contract to help the lowest-performing schools attract and retain good teachers.

Several students from West Philadelphia High School said that although they enjoyed their Teach for America instructors, the staffers were gone after two years. They said the schools need stable teaching staffs.

Wang said his office was working with the district to find ways to encourage corps members to remain beyond two years.

But he said that in Philadelphia and nationally, Teach for America has found that even corps members who do not stay in the classroom remain involved in education.

"Our whole theory is that we're recruiting the best and the brightest future leaders in the short term to work in the classroom," he said. "And in the long term they become lifelong advocates for affecting systemic change."

Contact staff writer Martha Woodall at 215-854-2789 or at martha.woodall@phillynews.com.