LOGUMKLOSTER, Denmark — The cluster of red brick buildings in a remote part of southern Denmark looks unremarkable from the outside, but this week, its classrooms housed some of the rarest people during the pandemic in today’s Europe.

Schoolchildren.

On Wednesday, 350 pupils returned to classes at the Logumkloster District School for the first time in a month, as Denmark became the first country in the Western world to reopen its elementary schools since the start of the coronavirus pandemic. It has turned the Danish education system into a laboratory for whether and how schools can function in an age of contagion.

“It is a new world,” said Tanja Linnet, the school’s head teacher, as pupils arrived early on Thursday morning. “We used to make plans for if there was a terrorist attack here — but never this kind of attack.”