With some public schools reopened and coronavirus cases already being reported, protesters in at least three dozen school districts across the country took to the streets Monday to demand that science and health concerns rule decisions about when and how to resume in-person learning.

Late Monday, in what could have been a response, President Trump repeated his call for schools to open by tweeting: “OPEN THE SCHOOLS.”

Trump’s demands that schools reopen while coronavirus infection rates are increasing in most states have politicized reopening decisions being made at the local and state levels. Many district leaders, including in Republican-led states, have said they are starting the school year virtually because it is too dangerous to reopen school buildings and risk the spread of the coronavirus.

Still, some districts have already begun the 2020-2021 academic year by reopening school buildings, and already coronavirus cases have been reported in some of them.

In Georgia’s Gwinnett County, some 260 employees tested positive or had possibly been exposed to the coronavirus a day after teachers returned to work last week and were told to stay home. Alcoa City Schools in Tennessee recently opened, but a few days later a student tested positive for the virus. At Corinth High School in Mississippi, in-person classes started last week and within days five students tested positive for the coronavirus and others went into quarantine as a result of contact tracing, the school district said.

In New York, Chicago, Los Angeles and other cities across the country on Monday, teachers, students, parents and others protested in car caravans and street marches, demanding that health concerns and scientific findings on the spread of the novel coronavirus dictate when and how schools reopen.

In what unions and other organizers called a national day of resistance against what they called “unsafe” school openings, protesters carried fake coffins and gravestones as well as signs demanding schools stay closed until it is safe to reopen, including New York City and Chicago, where school buildings are set to reopen soon. In Milwaukee, the Teachers’ Education Association tweeted pictures of protesters making fake gravestones that said, for example, “RIP GRANDMA CAUGHT COVID HELPING GRANDKIDS WITH HOMEWORK.”

In Baltimore, teachers and students and others protested outside a Comcast building to demand the company provide improved Internet service for students. The protest occurred on the same day Maryland Gov. Larry Hogan moved to invalidate a decision made by the health department in Montgomery County that said private schools should start the academic year online, just like public schools are.

One of those private schools is St. Andrews Episcopal School in Potomac, Md., where Trump’s son, Barron, attends.

(Update: More students test positive at Corinth High School.)

Here are some pictures and social media posts on the protests: