The Bill and Melinda Gates Foundation awarded Philadelphia $2.5 million Wednesday to promote collaboration between public and charter schools and fund projects aimed at boosting teacher training and principal leadership, among other things.

Philadelphia was one of seven cities nationwide to get Gates money, which will be distributed over three years. The public and charter school communities in each city - the others are Boston, Denver, Hartford, Conn., New Orleans, New York City, and Spring Branch, Texas - have signed agreements pledging cooperation and stating mutual goals.

Philadelphia's Great Schools compact also includes archdiocesan schools. As a group, the Great Schools participants aim, over five years, to replace 50,000 seats in struggling schools with seats in high-quality ones.

The money, to be managed by the nonprofit Philadelphia Schools Partnership, will fund three specific projects:

An urban leadership academy for principals at all three types of schools. Eventually, 50 promising leaders per year would enroll in the program, which would place them in full-year residencies.

A "teacher effectiveness" program. Currently in place at Mastery Charter Schools, the program includes intensive supports for teachers and will be expanded to include "hundreds" of educators in district, charter and parochial schools.

Mastery CEO Scott Gordon explained the program as "essentially describing what good teaching is, then providing the resources" for teachers to get there. "The intent is large impact and systemic change," Gordon said.

The creation of benchmark tests to align to the new Common Core standards adopted by schools around the country.

Flanked by district, charter, and parochial school officials and a representative from the Gates Foundation, Mayor Nutter's chief education officer, Lori Shorr, said that for years, the philanthropic community bypassed Philadelphia, whose district and charter schools were often at odds.

But in the last few years, the parties began to wonder: "If we were to stop fighting each other and use that energy for something else, what would that look like?" Shorr said at a City Hall news conference.

The Gates commitment is a sign that it's working, Shorr said.

Vicki Phillips, an education official at the Gates fund, praised the work that education leaders in the city have done.

"Many of Philadelphia's schools already have different kinds of management and leadership going on, and you are no stranger to any of that," Phillips said. "And we think that you have an opportunity here to set such an important example for the rest of the country."

Philadelphia School Superintendent William R. Hite Jr. said the Gates money would prove vital.

There is much work to be done, both in district schools and elsewhere, Hite said, and "that work cannot be done in silos," at it has in the past.

This is the second investment Gates has made in Philadelphia's compact. Soon after it was signed in late 2010, the foundation awarded $100,000 to help implement it.

Though the officials at Wednesday's City Hall event said the announcement meant great things for the city, some local education watchers have expressed concerns about the implications of accepting Gates money and worry that the Great Schools Compact shortchanges district schools.

Contact Kristen Graham at 215-854-5146, kgraham@phillynews.com and on Twitter @newskag. Read her blog, "Philly School Files," at www.philly.com/schoolfiles.