Human Rights Watch published a 33-page report Thursday based on more than 70 interviews conducted with students and teachers who fled the violence in Syria.
The report alleges pro- and anti-government forces in Syria were using schools for everything from sniper posts to detention centers.
"Schools should be havens, but in a country that once valued schooling, many Syrian children aren't even getting basic education and are losing out on their future," children's rights researcher Priyanka Motaparthy said in a statement from London.
A report published Tuesday by the International Commission of Inquiry on Syria said children as young as 12 years old were "routinely" arrested by government forces during protests. The report said a 2-year-old boy died in April after being shot by opposition forces in Damascus.
Human Rights Watch said it heard testimony that teachers were involved in the interrogation of school-age children.
"Both government forces and opposition armed groups have a responsibility to protect children's lives and their right to education," Motaparthy said. "By using schools for military purposes, they are putting children in harm's way and destroying their hopes for their future."