Moises Vazquez, 26, known as Spider-Moy, a computer science teaching assistant at the Faculty of Science of the National Autonomous University of Mexico (UNAM), who teaches dressed as a comic superhero Spider-Man, travels on a subway on his way to work in Mexico City, Mexico, May 27, 2016. REUTERS/Edgard Garrido SEARCH "SPIDERMAN TEACHER" FOR THIS STORY. SEARCH "THE WIDER IMAGE" FOR ALL STORIES TPX IMAGES OF THE DAY 

Moises Vazquez, 26, known as Spider-Moy, a computer science teaching assistant at the Faculty of Science of the National Autonomous University of Mexico (UNAM), who teaches dressed as a comic superhero Spider-Man, poses for a photograph during a class in Mexico City, Mexico, May 27, 2016. REUTERS/Edgard Garrido SEARCH "SPIDERMAN TEACHER" FOR THIS STORY. SEARCH "THE WIDER IMAGE" FOR ALL STORIES TPX IMAGES OF THE DAY 

Said Omar, a lecturer at the Garissa University College, teaches third-year students as they return to the campus in Kenya's northeast town of Garissa, January 11, 2016. The campus reopened today nine months after an attack by Somalia-based al-Qaeda linked al-Shabaab Islamist militants. REUTERS/Thomas Mukoya 

Said Omar, a lecturer at the Garissa University College, teaches third-year students as they return to the campus in Kenya's northeast town of Garissa, January 11, 2016. The campus reopened today nine months after an attack by Somalia-based al-Qaeda linked al-Shabaab Islamist militants. REUTERS/Thomas Mukoya 

Said Omar, a lecturer at the Garissa University College, teaches third-year students as they return to the campus in Kenya's northeast town of Garissa, January 11, 2016. The campus reopened today nine months after an attack by Somalia-based al-Qaeda linked al-Shabaab Islamist militants. REUTERS/Thomas Mukoya 

Said Omar, a lecturer at the Garissa University College, teaches third-year students as they return to the campus in Kenya's northeast town of Garissa, January 11, 2016. The campus reopened today nine months after an attack by Somalia-based al-Qaeda linked al-Shabaab Islamist militants. REUTERS/Thomas Mukoya 

Said Omar, a lecturer at the Garissa University College, teaches third-year students as they return to the campus in Kenya's northeast town of Garissa, January 11, 2016. The campus reopened today nine months after an attack by Somalia-based al-Qaeda linked al-Shabaab Islamist militants. REUTERS/Thomas Mukoya. REUTERS/Thomas Mukoya 

A student is helped by his teacher to build a dinosaur robot during the annual robotics fair supported by the Bolivian Education Ministry in La Paz, August 10, 2015. REUTERS/David Mercado 

A helper adjusts flowers outside the Albertville Realschule (school) before a memorial service in Winnenden March 21, 2009. A German teenager went on a killing rampage with his father's Beretta pistol, killing 12 students and teachers at his former school and three other people before shooting himself last week. REUTERS/Kai Pfaffenbach(GERMANY DISASTER CONFLICT SOCIETY) 

A Chinese teacher instructs her students how to spray disinfectant to kill
the SARS virus during a training course for domestic helpers in Beijing May
13, 2003. China's capital has started to clean up the city as part of
efforts to contain Severe Acute Respiratory Syndrome (SARS) which has
infected more than 5,000 people and killed about 252 across the vast
country. REUTERS/Wilson Chu PP03050042

ASW/FA 

A Chinese teacher instructs her students how to spray disinfectant to
kill SARS virus during a training course for domestic helpers in
Beijing May 13, 2003. China's capital has started to clean up the city
as part of efforts to contain Severe Acute Respiratory Syndrome (SARS)
which has infected more than 5,000 people and killed about 252 across
the country. REUTERS/Wilson Chu

ASW/RCS