Two Germantown High School students nearly killed a beloved math teacher during a trivial argument yesterday morning over an iPod, police said.

Frank Burd, 60, suffered three spinal fractures in the attack, a police source said, and was taken to Albert Einstein Medical Center, where he underwent surgery last night. A hospital spokeswoman said that following surgery, a stabilizing device called a "halo" was placed on his shoulders to support his neck. She said Burd was in critical but stable condition condition in intensive care.

The students - one in 11th grade, the other in 9th - last night were charged with aggravated assault, simple assault and reckless endangerment of another person, police said. They sat inside a holding cell last night in the 35th District, headquartered at Broad and Champlost streets, cops said.

The two were "immediately suspended and the paperwork for expulsion" was being prepared, said school district spokesman Fernando Gallard.

Burd, who teaches algebra and geometry, was teaching a class of 11th-graders when he noticed the 17-year-old boy playing with an iPod and took it from him, Gallard said.

At about 11:10 a.m., when the class was over, the teen walked up to the teacher and demanded back his trendy musical device, said the spokesman. Then the ninth-grader entered the fray.

Police said one of the teens punched Burd while the other tripped and kicked him to the floor.

Gallard said there were conflicting stories as to how Burd ended up on the floor with broken bones. One student witness said the ninth-grader shoved Burd, while another said the teacher had tripped and fallen during the war of words.

Burd has taught in city schools for more than 30 years.

As word spread of the attack throughout the school, staff called their union, the Philadelphia Federation of Teachers.

"It is absolutely unacceptable," said union vice president Jerry Jordan.

Jordan said Germantown lost their teachers' assistants this academic year, which has placed the teachers at a greater risk. *