The Centers for Disease Control and Prevention (CDC) has recently updated the K–12 school guidance. The agency now recommends that with universal masking, students should maintain a distance of at least 3 feet in classrooms. 

In elementary schools, the agency now recommends that all students should maintain a distance of at least 3 feet in classrooms with universal mask use – irrespective of the level of community transmission, whether low, moderate, substantial, or high. In middle and high schools, it is recommended that students should maintain a distance of at least 3 feet in classrooms where mask use is universal and in communities with low, moderate, or substantial transmission. It further recommends that middle school students and high school students should maintain a distance of at least 6 feet in communities where transmission is high, if cohorting is not feasible… (CDC, March 19, 2021)