JERUSALEM (AP) — Large numbers of students in U.N.-run schools in Gaza have flunked achievement tests in math and Arabic, the agency said Thursday, attributing the poor showing to violence, overcrowding and poverty.

More than two-thirds of students in grades four through nine failed math, and more than one-third did poorly in Arabic, said the U.N. Relief and Works Agency, which runs schools for more than half a million children of Palestinian refugees across the Arab world. Ninety percent of Gaza sixth-graders failed the math test, UNRWA said.

In contrast, Palestinian students at U.N. schools in Lebanon, Syria and Jordan are doing better than their counterparts in government schools, indicating that a stable environment is key to learning, UNRWA said.

The U.N. agency said it will try to improve results in Gaza by hiring 1,500 classroom assistants, decreasing class sizes to 30 students, adding more classes in Arabic and math, and building a teachers’ training college.

The achievement tests were administered during the summer at about two dozen U.N. schools in Gaza, for students in grades four through nine, said UNRWA spokesman Christopher Gunness.

The agency did not run tests in the West Bank.

Shaher Said, 13, who attends a U.N. school in the Shati refugee camp near Gaza City, said he has been distracted by violence. "How do you expect me to concentrate in my class?" he said. "If it’s not an Israeli air strike, it’s a friend of our family or a neighbor being killed in the internal confrontations."

Gaza’s children have been exposed to horrific violence for years, including gun battles fought right in their neighborhoods. Since the outbreak of the second Palestinian uprising in 2000, Israeli troops have frequently raided areas of Gaza to hunt Palestinian militants, and aircraft have fired missiles at wanted gunmen driving in crowded streets.

"The cumulative impact of years of violence and closures, of disrupted schooling and endemic poverty is clear from the stark exam results of Gaza’s school children," said John Ging, the UNRWA director in Gaza. "In spite of the challenging environment, we are determined to ensure that our reforms and our drive for excellence in UNRWA schools will be successful."

In all, about 195,000 children in Gaza, a territory with 1.4 million residents, attend U.N. schools.

-(The Associated Press) AP reporter Ibrahim Barzak contributed to this report from Gaza City.