More than 100 million children are out of school worldwide. Discrimination of marginalized groups by teachers and other students, long distances to school, formal and informal school fees, and the absence of inclusive education are among the main causes. Millions stop going to school to work long hours, often under hazardous conditions. Others experience violence or abuse from teachers or fellow students, or find their schools targets of armed attack. Families do not send girls to school, force them out of school to marry or girls are denied an education when they become pregnant. Many are kept from getting a secondary education because they cannot afford school fees. Even when in school, millions of children receive a poor quality education that leaves them lacking essential skills and knowledge.