It took another week before he was able to coax the staff and students back to school, he said.

The general breakdown in society has also eroded traditional classroom discipline. Several students linked to the Mahdi Army threatened their teachers if they did not help them pass exams, Halim said.

"The situation was better" under Saddam Hussein, he said. "There was security and the students used to respect their teachers."

On Monday, students at the Sahel Ibn Saad high school in Sadr City had to study in the faint sunlight coming through dirty windows because of a power outage. Their desks were cracked, and chunks of paint had chipped off the yellow walls.

A Quranic verse pasted over the blackboard in one class read: "God, make this country peaceful." Next to it was a picture of Muqtada al-Sadr and a quote from the anti-American Shiite cleric calling on Iraqis to unite to force out "the occupiers."

Abdul-Karim, the high school senior, said four of his teachers at the school quit because of the violence and were replaced by new college graduates with no experience. Only 300 of the school's 800 students show up anymore, and many of the classes are mostly empty, he said.

He makes it to school only three days a week because violence often blocks his path. His grade-point average has plunged from about 80 to 65, he said. Nevertheless, he hopes to attend college next year and plans to become a journalist to "report the truth and the misery of my people," he said.

Another student at the school, Ahmed Shawal, said he wanted to be a doctor — "but in such conditions I don't think I'll be able to achieve my ambition."

While many schools are indirectly affected by the violence, others are intentionally targeted, said Hussein, the spokesman for the Education Ministry. Last week, gunmen broke into a primary school in Khalis, 50 miles north of Baghdad, grabbed a teacher and his wife and killed them execution style in front of the horrified students, he said. The motive of the attack was not clear.

More than 300 teachers and Ministry of Education employees were killed last year, and 1,158 were wounded, the ministry reported. A U.N. report released last month said the killings continued "at an alarming level" this year.

The attacks have paralyzed the government's plan to build 1,000 new schools this year and even forced it to close existing schools across the country, Hussein said.

Ahmed Qassim, a 19-year old student at Nissour High School in the northern city of Mosul, was forced to miss three exams during the first semester last year because the bridges linking his house to his school were sealed off. He had to miss the whole second semester because of insecurity.

Now he is repeating his senior year.