A teacher(L) greets a first grader at Taipinglu Primary School in Haidian District, Beijing, capital of China, Aug. 29, 2020. Students of senior high schools, first and third grades of junior high schools, and first grade of primary schools returned to school in Beijing on Saturday. (Xinhua/Ren Chao) 

First graders have class at Taipinglu Primary School in Haidian District, Beijing, capital of China, Aug. 29, 2020. Students of senior high schools, first and third grades of junior high schools, and first grade of primary schools returned to school in Beijing on Saturday. (Xinhua/Ren Chao)

Teachers greet a first grader at Taipinglu Primary School in Haidian District, Beijing, capital of China, Aug. 29, 2020. Students of senior high schools, first and third grades of junior high schools, and first grade of primary schools returned to school in Beijing on Saturday. (Xinhua/Ren Chao)

Students wearing face masks are seen at class with their teacher at High School Affiliated to Beijing Institute of Technology in Beijing, capital of China, Aug. 29, 2020. Students of senior high schools, first and third grades of junior high schools, and first grade of primary schools returned to school in Beijing on Saturday. (Xinhua/Zhang Chenlin)

A first grader gets her temperature checked with the help of a teacher before entering the campus at Dongshengshiyan Primary School in Haidian District, Beijing, capital of China, Aug. 29, 2020. Students of senior high schools, first and third grades of junior high schools, and first grade of primary schools returned to school in Beijing on Saturday. (Xinhua/Li He)

First graders are seen in a classroom at Dongshengshiyan Primary School in Haidian District, Beijing, capital of China, Aug. 29, 2020. Students of senior high schools, first and third grades of junior high schools, and first grade of primary schools returned to school in Beijing on Saturday. (Xinhua/Li He)

First graders have class at Taipinglu Primary School in Haidian District, Beijing, capital of China, Aug. 29, 2020. Students of senior high schools, first and third grades of junior high schools, and first grade of primary schools returned to school in Beijing on Saturday. (Xinhua/Ren Chao)

A teacher leads a first grader into the campus at Dongshengshiyan Primary School in Haidian District, Beijing, capital of China, Aug. 29, 2020. Students of senior high schools, first and third grades of junior high schools, and first grade of primary schools returned to school in Beijing on Saturday. (Xinhua/Li He)

Students perform on the school opening ceremony at High School Affiliated to Beijing Institute of Technology in Beijing, capital of China, Aug. 29, 2020. Students of senior high schools, first and third grades of junior high schools, and first grade of primary schools returned to school in Beijing on Saturday. (Xinhua/Zhang Chenlin)

Students have class at High School Affiliated to Beijing Institute of Technology in Beijing, capital of China, Aug. 29, 2020. Students of senior high schools, first and third grades of junior high schools, and first grade of primary schools returned to school in Beijing on Saturday. (Xinhua/Zhang Chenlin)

A first grader poses for photos at Dongshengshiyan Primary School in Haidian District, Beijing, capital of China, Aug. 29, 2020. Students of senior high schools, first and third grades of junior high schools, and first grade of primary schools returned to school in Beijing on Saturday. (Xinhua/Li He)

Students wearing face masks get their health QR code checked before entering the campus of High School Affiliated to Beijing Institute of Technology in Beijing, capital of China, Aug. 29, 2020. Students of senior high schools, first and third grades of junior high schools, and first grade of primary schools returned to school in Beijing on Saturday. (Xinhua/Zhang Chenlin)

First graders raise their hands during a training class at Taipinglu Primary School in Haidian District, Beijing, capital of China, Aug. 29, 2020. Students of senior high schools, first and third grades of junior high schools, and first grade of primary schools returned to school in Beijing on Saturday. (Xinhua/Ren Chao)

Students and their parents queue to get their temperature checked at Taipinglu Primary School in Haidian District, Beijing, capital of China, Aug. 29, 2020. Students of senior high schools, first and third grades of junior high schools, and first grade of primary schools returned to school in Beijing on Saturday. (Xinhua/Ren Chao)

A teacher demonstrates how to wear a face mask at class at Dongshengshiyan Primary School in Haidian District, Beijing, capital of China, Aug. 29, 2020. Students of senior high schools, first and third grades of junior high schools, and first grade of primary schools returned to school in Beijing on Saturday. (Xinhua/Li He)

Students wearing face masks get their temperature checked before entering the campus of High School Affiliated to Beijing Institute of Technology in Beijing, capital of China, Aug. 29, 2020. Students of senior high schools, first and third grades of junior high schools, and first grade of primary schools returned to school in Beijing on Saturday. (Xinhua/Zhang Chenlin)

A teacher leads a first grader into the campus at Dongshengshiyan Primary School in Haidian District, Beijing, capital of China, Aug. 29, 2020. Students of senior high schools, first and third grades of junior high schools, and first grade of primary schools returned to school in Beijing on Saturday. (Xinhua/Li He)

First graders walk with their parents at Taipinglu Primary School in Haidian District, Beijing, capital of China, Aug. 29, 2020. Students of senior high schools, first and third grades of junior high schools, and first grade of primary schools returned to school in Beijing on Saturday. (Xinhua/Ren Chao)