A small but growing number of school districts across the country are moving to a four-day week, in a shift they hope will help close gaping budget holes and stave off teacher layoffs, but that critics fear could hurt students' education.

State legislators and local school boards are giving administrators greater flexibility to set their academic calendars, making the four-day slate possible. But education experts say little research exists to show the impact of shortened weeks on learning. The missed hours are typically made up by lengthening remaining school days.

Of the nearly 15,000-plus districts nationwide, more than 100 in at least 17 states currently use the four-day system, according to data culled from the Education Commission of the States. Dozens of other districts are contemplating making the change in the next year—a shift that is apt to create new challenges for working parents as well as thousands of school employees.  More here.