A study of New York City charter schools that found a strong link between the amount of instructional time students got and their achievement is being held up as an evidence for a national push for longer school days.

Roland Fryer, the Harvard University researcher who completed the study, found in a different investigation that student test scores inched up — by about .015 points per day of school — in years with few snow days.

Fryer spoke during a press call this morning announcing the debut of the Time to Succeed Coalition, which is calling for schools to expand their day and year — an often controversial proposition. It also calls on schools to redesign the way they use time in order to beef up the curriculum and ensure students get a well-rounded education.

The coalition’s chairs are Chris Gabrieli, the longtime extended-day advocate who chairs the National Center on Time & Learning, and Ford Foundation president Luis Ubiñas. They have attracted more than 100 coalition members from across state, sector, and political lines, ranging from the CEO of Netflix to the president of the NAACP. Mayor Michael Bloomberg, Chancellor Dennis Walcott, and State Education Commissioner John King have all signed on as well, committing to prioritize the expansion and redesign of school time in the coming years.

During the call, Ubiñas called the formation of the coalition a “seminal moment” and said that the proof  is in the performance of the thousands of schools across the country that have implemented longer school days. Over the next three years, the Ford Foundation will be investing at least $50 million to help schools add time, with a special emphasis on helping schools that serve low-income students.

The goal of the coalition is to raise awareness among decision-makers, by encouraging them to use the federal School Improvement Grants and the No Child Left Behind waiver process to expand and redesign school time. It also aims to build up a grassroots movement, rallying teachers, communities, and civil rights groups for the cause. Over the next two years, the hope is to double the number of schools across the country that offer more instructional time to their students.

Randi Weingarten, president of the American Federation of Teachers; Newark Mayor Cory Booker; and Jeff Smith, superintendent of Arizona’s Balsz school district all joined in on the call as well, touting the importance of more school.

In 2009, Smith took President Barack Obama’s call to rethink the school day to heart and upped the Balsz calendar to 200 days. In the last two years, his students have closed the test score gap between their district and the rest of the state by over two thirds.

While more time seems like it might equate to more money, Gabrieli said there are creative options like staggering teacher start time and leaning on community partners that could make extending the school day affordable.

Weingarten was president of the city’s teachers union in 2006, when the UFT agreed to extend the school day by 37.5 minutes four days a week in exchange for a pay increase. Today, she said she is confident teachers will support Time to Succeed, and that one of her roles as union president is also to ensure that teachers are compensated fairly for their additional time.

“There’s this crazy ideal if you work harder and longer you get better results,” Booker said. “But it actually proves true.”