A United Nations report says about half of students aged 13 to 15 worldwide have experienced some form of violence in school. This number represents about 150 million students from around the world. The report was released by the U.N. children’s agency, known as UNICEF. Included in the 13-15 age group were students who reported being in a physical fight within the past year. Also included were students who said they had been bullied in the last month. “For millions of students around the world, the school environment is not a safe space to study and grow,” the report said. “It is a danger zone where they learn in fear.” Some information in the study was collected by UNICEF. Information on some countries came from governments or other organizations. The report identifies bullying as one of the biggest problems facing schools.