Would students learn more — and perform better on those all-important standardized tests — if they spent more time in school?

President Obama thinks so. "I know longer school days and school years are not wildly popular ideas," he said recently as he promoted his education initiatives. "But the challenges of a new century demand more time in the classroom."

Local educators and the teacher's union have also voiced support for longer school days. After all, more hours in a school day means more instruction, which means more learning, right?

Well, that depends.

Numerous studies, practical experience and common sense suggest that the quality of education depends more on the quality of the educators than the number of hours they log.

A report to the 2009 Legislature by the state Department of Education acknowledges a lack of empirical evidence linking a longer day to better student performance.

National studies, including those reviewed in 2007 by the Education Sector think tank, show that the quality of instructional time — not the amount — is most important.

In any event, with the state in the throes of an unprecedented fiscal crisis, expanding the workload — and pay — of teachers will be impossible in the near future.

Those who support a longer school day cite several benefits: Disadvantaged students, who may have no educational resources outside school, could get more instructional time; "block scheduling," now being used at several O'ahu schools, allows for longer, more focused classes with fewer disruptions; and struggling students could get additional help to boost grades.

These are all reasonable goals. But achieving them has less to do with the number of hours in the day than with how those hours are used.

At Farrington High School, which uses block scheduling to lengthen the school day, scores have improved, but not necessarily because of the schedule, principal Catherine Payne acknowledges.

Rather, success has depended on the fundamentals: Skilled teachers who can keep students focused for 85-minute classes, especially in subjects like mathematics; teachers and administrators cognizant of the unique needs of individual students; and teachers who, with their union, are flexible enough to adopt needed changes willingly and with enthusiasm.

If that happens, students will learn more, teachers will teach more and the school day will be more productive — whatever its length.