Mastery Charter Schools has been awarded $1.5 million from the Philadelphia School Partnership to help it turn around the Frederick Douglass Charter School in North Philadelphia.

The grant from the partnership's Great Schools Fund was scheduled to be announced Wednesday - the first day of school for students at Douglass and at Mastery's 14 other campuses across the city.

"We're delighted to have the support of the Philadelphia School Partnership and to get the resources we need to provide the best quality education for the children at Frederick Douglass," said Scott Gordon, CEO of the nonprofit Mastery Schools.

Douglass is a former low-performing district elementary school at 2118 W. Norris St. In 2010, the School Reform Commission turned it over to Scholar Academies to operate as a charter under the district's Renaissance program.

Scholar Academies made improvements, but did not produce the academic gains at Douglass it had promised. Mastery was tapped last spring to take over the K-8 school with 750 students.

The SRC approved the change in May for the 2015-16 academic year.

Mastery has converted 12 former district schools into charters, but Douglass is the first Renaissance charter to be targeted for academic overhaul.

Jessica Pena, who directs the partnership's Great Schools Fund, said the grant would help Mastery bring its successful model to Douglass.

A 2013 district analysis of turnaround schools showed that reading and math performance at Mastery schools had improved by 14 percentage points on average.

"We have invested in Mastery before," Pena said. "This grant brings our total investment to $7.7 million."

Mastery will use the latest grant to introduce its curriculum and teacher coaching programs to Douglass and to add resources and technology.

Pena said Mastery and Scholar Academies worked to ensure a smooth transition for Douglass students and their families.

Gordon said Mastery had pledged to offer jobs to all the Douglass teachers that Scholar Academies had offered contracts for the fall.

Of the 56 teachers, 42 have remained. Gordon said that Mastery promised to give teachers the training and support they needed to be successful.

"We believe that a great school is great teachers," Gordon said.

Mastery offered training sessions for Douglass teachers in June and wrapped up three more weeks this month.

Sam Biddle, 27, who began teaching second grade at Douglass in 2012, is among those who stayed.

He said that when the charter's future was in doubt, he and other staffers were worried about their students and their families.

"This school historically has been a center and cornerstone of this neighborhood," Biddle said. "I wanted to be sure our kids and the neighborhood had that."

He was heartened when parents and the community said they wanted to build on the foundation that Scholar Academies had created at Douglass. Biddle was relieved Mastery was taking over Douglass.

"I really felt this was a great mix for our kids," Biddle said.

"We had become a decent neighborhood school," he said. "Under Mastery, we are heading in the direction of being a great neighborhood school."

A native of Mount Airy, Biddle is an older brother of Jesse Biddle, the Phillies pitching prospect. Biddle said his brother had read to his second graders at Douglass.

And when Jesse Biddle takes the mound with the Lehigh Valley Iron Pigs, Biddle said he wears wrist bands printed with the mottos that his second graders chose for their classroom: "Challenge yourself," "Explore your world," and "Try love first."

Mastery, which began as a single charter school with a college-prep focus in 2001, is a network of 15 schools with nearly 10,000 students.

The Philadelphia School Partnership was founded in 2010, and set a goal of raising $100 million to ensure more city students have access to high-quality schools. Its Great Schools Fund aims to add 35,000 seats in successful public, charter, and Catholic schools by 2016-17.

Its funding comes from a variety of sources, including the Bill and Melinda Gates Foundation, the Walton Family Foundation, and the William Penn Foundation.

martha.woodall@philly news.com215-854-2789@marwooda