A coach wipes away tears and comforts a girl who was feeling tired during gymnastics lessons at the Shanghai Yangpu Youth Amateur Athletic School in Shanghai, China, May 4, 2016. (Photo by Aly Song/Reuters)

A boy dressed like Hindu Lord Krishna waits to attend celebrations on the eve of Janmashtami at a school in Mumbai, India, Friday, September 4, 2015. The day marks the birth of Krishna. (Photo by Rajanish Kakade/AP Photo)

School girls stand next to a ballot box at a polling station during the municipal elections in Havana April 19, 2015. Cuba held its first local elections since a historic thaw in relations with the United States with an unusual wrinkle in the single-party system: two of the 27,000 candidates openly oppose the government. (Photo by Reuters/Stringer)

School boys who attend Sri Lankan traditional dance training wait for their graduation ceremony at a Buddhist temple in Colombo, Sri Lanka January 23, 2017. (Photo by Dinuka Liyanawatte/Reuters)

A reveller of the Salgueiro samba school performs during the second night of Rio's Carnival at the Sambadrome in Rio de Janeiro, Brazil, on February 13, 2018. (Photo by Mauro Pimentel/AFP Photo)

A boy doing chin-ups as he takes entrance exams at the Moscow Suvorov Military School in Moscow, Russia on July 11, 2019. (Photo by Sergei Karpukhin/Russian News Agency TASS via Getty Images)

Students dressed up as Hindu gods Lord Krishna and Lord Shiva participate in a cultural event in their school in Mumbai, India on August 21, 2019. (Photo by Indranil Mukherjee/AFP Photo)

A reveller from Unidos da Tijuca samba school performs during the first night of the Carnival parade at the Sambadrome in Rio de Janeiro, Brazil on March 4, 2019. (Photo by Pilar Olivares/Reuters)