The UN children agency or UNICEF says 70 percent of the 1, 200 schools in major conflict hit areas remain closed.
In a statement the agency said 36 schools of the 1, 200 are used for military purposes.
More than 12 thousand children were recruited by the warring parties including 89 schoolboys abducted one month ago from Wau Shilluk in Upper Nile State.
UNICEF continues to call for the release of hundreds of abducted children.
The agency says 200 thousand of target children and adolescents supposed to go back to school are in conflict states.