On one hand, the Time for Innovation Matters in Education Collaborative is a welcome chance for us to shake off the anachronistic trappings of the agrarian school calendar. After all, just because we went to school from August to June doesn’t mean our kids should, and just because we got out of school at 3 p.m. doesn’t mean that dismissal time is a good idea. In fact, for poor kids in poor communities, the period between 3 and 6 p.m. is the most dangerous time of the day. So I take great hope in the project’s intent to “empower each student with the knowledge, skills, and experiences essential for college and career success.”

And I admire any plan to expand the sorts of learning experiences students have during the day - and where (and how) the day unfolds. As the Ford Foundation’s Jeannie Oakes puts it, “More time must mean better time.”

On the other hand, the 40 schools participating in this project in Colorado, Connecticut, Massachusetts, New York and Tennessee, don’t exist in a vacuum, and here in America we still rank schools as successful or unsuccessful based on a single metric - standardized reading and math scores.  Knowing that, will these schools be able to follow through on their plans to explore academic content more deeply, provide teacher collaboration time more regularly and revitalize the arts more fully? Or will the extra hours be used to turn a small subset of “failing” schools into high-achieving ones?

It’s too soon to tell, of course, but as the work begins, we might want to pay attention to the stories of the world’s two highest-achieving school systems: those in Finland and Shanghai.

In Shanghai, students are in school for an average of nine hours a day - and driving improvement in test scores is the primary goal. As Peking University High School deputy principal and teacher Jiang Xueqin put it in an interview with NBC, “It’s a test-oriented education system, which means that students are taught from a very early age how to beat tests.”

That sort of focus is clearly a recipe for soaring scores. It also comes with a cost. “In terms of management, artistic, or creative talent, China’s tremendously lacking,” Jiang added. “That’s going to hamper China’s ability to compete globally - especially with the United States.”

By contrast, Finland has the world’s best system of public schools - and among the shortest school days. Students don’t even start their formal education until they turn 7, and the average day ends somewhere between noon and 2 p.m.

Unlike in America, however, Finland invests deeply in a social safety net for its citizens, has low rates of poverty and requires no national exams. “There's no word for accountability in Finnish,” said Pasi Sahlberg, one of the chief architects of Finland’s successful school reforms. “Accountability is something that is left when responsibility has been subtracted.”

Which of these two paths would you prefer for America’s schools? To me, there are valuable lessons in both: As in Shanghai, I think there is great value in lengthening the school day, as long as doing so is truly a way to help poorer kids experience the sorts of enrichment opportunities that richer kids take for granted. And as in Finland, there is great merit in re-imagining how we define success or failure in our schools.

We can do both - drive achievement and deepen the learning experience - but not without deciding which of the two is our primary goal, and not without making some changes that go a lot deeper than 300 extra hours a year.