Ask parents how much time their students spend in school, and many answer, "Not enough."

Ask students, and many say, "Too much."

Ask the public, and the answer might be, "Less than students in other countries." Is that really true?

"There is a perception among policymakers and the public that U.S. students spend less time in school than students in other countries," reports The Center for Public Education in its study of instructional hours called "Time in School: How Does the U.S. Compare?"

In fact, U.S. Education Secretary Arne Duncan once said children in India and China go to school 25 to 30 percent longer than children in the U.S. Researchers for the center started their evaluation with this comparison.

Calculations of U.S. instructional hours show that hours spent in school vary according to state mandate, with most states requiring between 175 and 180 days of school—which translates into between 900 and 1,000 instructional hours per year.

The center's researchers found that, in India, students at the middle school level spend 220 days a year in the classroom, but their 1,000 instructional hours mirror those in much of the U.S. China middle school students receive a similar number of instructional hours.

Other countries' hours of instruction for middle school students (for the sake of comparison here) were:

Korea, Finland, and Japan are all considered high-performing countries, based on their students' scores on international tests.

For parents and the public, the center's study comes to this conclusion:

"The U.S. does not require schools to provide less instructional time than other countries. Basing policy decisions on this false perception alone could be costly and provide no clear benefits. Providing extra time is only useful if that time is used wisely. As the Center's report "Making Time" found, the relationship between time and student learning is not about the amount of time spent in school. Rather, it is how effectively that time is used.

"And this report has also shown that there is no relationship between simply requiring more time and increased achievement. The data shows that a number of countries that require fewer hours of instruction outperform the U.S., while the U.S. performs as well as or better than some other countries that require more hours of instruction."

More from "Time in School: How Does the U.S. Compare?" is available here, and from the center's earlier "Making Time" report, which covers what happens when more time is devoted to instruction,here.