Schedules get a makeover in many schools

The Achievement System's calendar, which includes more than 1,600 hours of instruction, will be among the longest in the country. The national average for schools with extended learning time is 1,200 hours, according to the NCLT.

However, some research suggests that the amount of time spent in schools isn't as important as how it is used. A 2009 National Academy of Education white paper suggests that expanded learning time only yields significant gains if it's accompanied by high-quality teaching. It recommends using an expanded schedule for extra-curricular activities, such as sports or music, or programs in the summer.

In some states, the concern is that a longer school calendar will harm the economy. Under Alabama's Flexible School Calendar Act, passed last month, school districts in the state can't start earlier than two weeks before Labor Day and must end by Memorial Day. Supporters say it will boost tourism in the state, particularly on the Gulf Coast, and bring in up to $22 million in extra tax revenue annually.

The "flexibility" of the measure, which had the strong backing of the tourism industry, is that it allows schools to lengthen the school day as long as they stay within the prescribed dates.

Alabama Gov. Robert Bentley vetoed the measure, arguing that districts should be allowed to opt out. Bentley also questioned whether it would provide the economic boost predicted by its backers.

"Tourism has seen strong numbers in the past year," Bentley's spokesman Jeremy King said in an email. "That would indicate the school calendar has not been a hindrance to strong tourism in this state."

But Alabama lawmakers overrode Bentley's veto, making Alabama one of 13 states that mandate start or end dates, according to the Education Commission of the States.

Tourism also has been an issue in Virginia. During his State of the Commonwealth address in January, Virginia Gov. Bob McDonnell urged lawmakers to rescind a requirement that schools not start before Labor Day. The majority of districts in the state have received waivers from the requirement, but an effort to repeal the so-called "Kings Dominion Law," so named for the amusement park 25 miles north of the Virginia capital, died in a Senate committee this past session.