Longer winter breaks and shorter summer vacations are ideas being tested around the country as school districts debate whether to extend the school year.

U.S. Education Secretary Arne (AHR'-nee) Duncan is pushing this extended school year — and it's an issue that's leading to heated debate.

Proponents say studies show students lose critical knowledge during the summer months away from school. Backers of a longer school year also say the U.S. is losing ground globally to compete.

Critics of the idea want to preserve what many families say is a precious respite from the school calendar — and allow for family vacations, outdoor play and more targeted learning.

A new pilot project will add school hours in districts in five states this year.