A woman waits to hear about her sister, a teacher, following a shooting at the Sandy Hook Elementary School in Newtown, Connecticut. A man killed his mother at their home and then opened fire inside the elementary school where she taught, massacring 26 people, including 20 children, as youngsters cowered in fear to the sound of gunshots reverberating through the building and screams echoing over the intercom. (Photo by Jessica Hill/Associated Press)

In this May 14, 2016 photo, children wearing their school backpacks climb on a cliff using a bamboo ladder on their way home from school in Zhaojue county, southwest China's Sichuan province. A village in China's mountainous west where schoolchildren must climb an 800-meter (2,625-foot)-high bamboo ladder secured to a sheer cliff face may get a set of steel stairs to improve it's safety. (Photo by Chinatopix via AP Photo)

Costume details featuring Joao Candido, a black sailor who led a revolt against the physical punishment of Brazilian Navy soldiers at the beginning of the 20th century, lie inside the Paraíso do Tuiuti Samba school at the Samba City complex in Rio de Janeiro, Brazil, Tuesday, January 16, 2024. Samba schools are gearing up for this year's Carnival, scheduled from Feb. 9-17. (Photo by Bruna Prado/AP Photo)

Members of Tom Maior Special Group samba school perform during the carnival parade at the Anhembi Sambadrome in Sao Paulo, Brazil, 22 Febr​uary 2020. Carnival is the biggest and most popular celebration in Brazil. (Photo by Sebastiao Moreira/EPA/EFE)

A reveller from Unidos da Tijuca samba school performs during the second night of the carnival parade at the Sambadrome in Rio de Janeiro, Brazil, February 28, 2017. (Photo by Ricardo Moraes/Reuters)

Mr. Zhong Hua, of Johns Hopkins University School of Medicine, took this image of the peripheral nerves (those outside of the brain) in an 11.5-day-old mouse embryo, magnified five times. (Photo by Zhong Hua)

Lucie Clayton instructs pupils in the art of correct posture by balancing a glass and book on their heads at her finishing school in Old Cavendish Street, London. (Photo by William Vanderson/Fox Photos/Getty Images). 25th November 1936

A performer from the Academicos do Grande Rio samba school dances during carnival celebrations at the Sambadrome in Rio de Janeiro, Brazil, early Monday, February 16, 2015. (Photo by Silvia Izquierdo/AP Photo)