WASHINGTON — In a significant revision of its school reopening guidelines, the Centers for Disease Control and Prevention announced Friday that students can be spaced 3 feet apart in classrooms.

“Physical distancing of at least 3 feet between students can safely be adopted in classroom settings where mask use is universal and other prevention measures are taken,” the CDC said in a statement.

The previous guidance, of 6 feet between desks, was widely seen as hampering school reopenings because many schools simply did not have the space or staff to make that accommodation and still have all students learning in person at the same time.

Mask use is critical to the new