A growing number of states are considering proposals to lengthen to school year by shortening the time kids spend outside of class in the summer. The longer-school-year option has notched up a number of high-profile supporters, counting among them the current U.S. Secretary of Education, Arne Duncan.

Duncan argues that summer vacations are so long that students frequently forget what they learned the previous year when they get back to class. That means a substantial chunk of the fall term is spent covering material that has been extensively covered the previous spring.

Duncan is overseeing a pilot program which will go into effect next fall in New York, Tennessee, Colorado, Connecticut and Massachusetts that will add as many as 300 additional hours of study to the average school year. In total, 40 schools enrolling nearly 20,000 students will be participating.

Proponents argue that too much knowledge is lost while American kids wile away the summer months apart from their lessons. The National Summer Learning Association cites decades of research that shows students’ test scores are higher in the same subjects at the beginning of the summer than at the end. “The research is very clear about that,” said Charles Ballinger, executive director emeritus of the National Association for Year-Round School in San Diego. “The only ones who don’t lose are the upper 10 to 15 percent of the student body. Those tend to be gifted, college-bound, they’re natural learners who will learn wherever they are.”

But support for lengthening the year is by no means universal. Opponents are claiming that lengthy breaks from school are important for childhood development, as well as providing flexibility for parents that is non-existent during the other three seasons of the year. Furthermore, although the summer loss is a real phenomenon that has been observed, there is yet no research that proves that shortening the summer vacation actually provides tangible academic benefits.

“I do believe that if children have not mastered a subject that, within a week, personally, I see a slide in my own child,” said Tina Bruno, executive director of the Coalition for a Traditional School Calendar. “That’s where the idea of parental involvement and parental responsibility in education comes in, because our children cannot and should not be in school seven days a week, 365 days a year.”

In the past, a number of districts that have experimented with longer academic year returned to the traditional schedule shortly thereafter, citing parental concerns as well as the cost as chief reasons why.

Parents and educators aren’t the only ones reporting reservations. Members of the tourism industry who rely heavily on family travel during the summer feel that shortening the summer break will have a negative impact on their fiscal health.