Elementary students wearing face masks are seen in a classroom during a trial face-to-face learning activity amid the COVID-19 outbreak at a school in Jakarta, Indonesia, June 9, 2021. (Photos: Xinhua/Agung Kuncahya B.)

Elementary students wearing face masks are seen in a classroom during a trial face-to-face learning activity amid the COVID-19 outbreak at a school in Jakarta, Indonesia, June 9, 2021.

An elementary student wearing a face mask is seen in a classroom during a trial face-to-face learning activity amid the COVID-19 outbreak at a school in Jakarta, Indonesia, June 9, 2021.

Elementary students wearing face masks are seen in a classroom during a trial face-to-face learning activity amid the COVID-19 outbreak at a school in Jakarta, Indonesia, June 9, 2021.

An elementary student wearing a face mask is seen in a classroom during a trial face-to-face learning activity amid the COVID-19 outbreak at a school in Jakarta, Indonesia, June 9, 2021.