Yemeni students listen to a lesson inside a classroom at their school in Sanaa, Yemen, on Oct. 27, 2018. Education has been one of the biggest casualties of the war in Yemen. "More than 135,000 Yemeni teachers have not received their salaries in more than two years," said UNICEF Executive Director Henrietta Fore in a press release on Oct.23. (Xinhua/Mohammed Mohammed)