Public schools in Los Angeles and San Diego, the two largest public school districts in California, will not be sending children back to campuses next month and will instead administer online classes due to concerns over the ongoing threat of the coronavirus.Why it matters: The two districts, which together enroll about 825,000 students, are the largest in the country thus far to announce that they will not return to in-person learning in the fall, even as the Trump administration aggressively pushes for schools to do so.Both President Trump and Education Secretary Betsy DeVos have threatened to withhold federal funds from schools that don't reopen, with DeVos arguing on Sunday that the money should be redirected to families who can use it to find other options for their children.California, one of several states that have seen a surge of coronavirus infections in recent weeks, reported a seven-day average on Sunday of more than 8,500 new cases per day.What they're saying: "This announcement represents a significant disappointment for the many thousands of teachers, administrators and support staff, who were looking forward to welcoming students back in August," the school districts said in a joint statement Monday."Most of all, this decision will impact our students in ways that researchers will take years to understand.""The federal government must provide schools with the resources we need to reopen in a responsible manner." By the numbers: United Teachers Los Angeles said Friday that 83% of 18,000 members polled said schools should not physically reopen in August. LA schools employ about 75,000 people.The big picture: Some school districts like New York City are exploring a hybrid model of learning, in which students rotate their days between in-person and online classes.The Los Angeles and San Diego districts will continue the online instruction they have been providing since mid-March. Several other large districts, including Santa Clara, Oakland and San Bernardino, have already established that their classes will remain online for now.Yes, but: District officials have noted that plans currently in place are dependent on their regions' local infection rates and testing and that schools must be ready to change on a whim. Go deeper: How Trump's push to reopen schools could backfire