SOUTH KOREA (WPRI) — High school seniors in South Korea went back to school on Wednesday, but some students weren’t able to complete their first day.

South Korean schools are planning to take back younger grades in phases — starting with high school seniors — with hopes of having every student back in class by June 8.

Strict measures are in place to prevent students from spreading COVID-19, which has kept students from entering the classroom for 11 weeks. The new school year typically begins on March 2.

Lines keep students six feet apart as they await a thermal camera to take their temperature — this happens twice a day, for both faculty and students.

Desks in classrooms are at least three feet apart, and masks have to be worn throughout the day with the exception of eating meals. Plastic partitions are placed in between where students can sit, and many seats are left empty.

Kim Seung-Kyeom serves as the principal at Joonkyung High School. In a translated interview with CNN, he said the preparation to welcome back students has been underway for weeks, but he understands the risk of doing so.

“I’m so happy to see my students back again after a long wait, the students can now begin their school life,” Seung-Kyeom said. “If we get a confirmed case, the school will immediately shut and return to online classes.”

According to the LA Times, 66 different high schools in one district in Incheon sent home students after just two periods, when they learned one student tested positive on Wednesday.