Pupils arrive at the campus of a primary school on the first day of the new school year in Nice, southern France, Sept. 1, 2020. The new school year kicked off on Monday in France where millions of students went back to classroom amid worrying epidemic situation, with safety concerns overshadowing the joy of "la rentree." (Photo by Serge Haouzi/Xinhua)

A teacher wearing a protective mask teaches in her classroom on the first day of the new school year in Nice, southern France, Sept. 1, 2020. The new school year kicked off on Monday in France where millions of students went back to classroom amid worrying epidemic situation, with safety concerns overshadowing the joy of "la rentree." (Photo by Serge Haouzi/Xinhua)

Pupils arrive at the campus of a primary school on the first day of the new school year in Nice, southern France, Sept. 1, 2020. The new school year kicked off on Monday in France where millions of students went back to classroom amid worrying epidemic situation, with safety concerns overshadowing the joy of "la rentree." (Photo by Serge Haouzi/Xinhua)

A staff member controls the traffic outside a school on the first day of the new school year in Nice, southern France, Sept. 1, 2020. The new school year kicked off on Monday in France where millions of students went back to classroom amid worrying epidemic situation, with safety concerns overshadowing the joy of "la rentree." (Photo by Serge Haouzi/Xinhua)

Students and teachers wearing protective masks attend a class at a high school on the first day of the new school year in Nice, southern France, Sept. 1, 2020. The new school year kicked off on Monday in France where millions of students went back to classroom amid worrying epidemic situation, with safety concerns overshadowing the joy of "la rentree." (Photo by Serge Haouzi/Xinhua)

Pupils arrive at the campus of a primary school on the first day of the new school year in Nice, southern France, Sept. 1, 2020. The new school year kicked off on Monday in France where millions of students went back to classroom amid worrying epidemic situation, with safety concerns overshadowing the joy of "la rentree." (Photo by Serge Haouzi/Xinhua)