He's a catalyst, a poster boy, and possibly a turning point in the violence against teachers in Philadelphia public schools that has persisted for years.

It's not a role he ever wanted, or imagined.

He wanted to be a catalyst for his neediest students. "They're lost. They're hurt. . . . I try to give them something. I try to give them me. "

Now, as the math teacher recovers from surgery and faces the process of rehabilitation, he is coming to terms with his new role, "if it's a cause that keeps people safe. "

Burd's injuries drew national media attention and ignited complaints from Philadelphia teachers and their union, who contended that violence against teachers was on the rise in the 174,000-student district and underreported by some principals who want to make their schools look good.

District officials and city police last week announced more stringent penalties for students who attack school personnel and took away discretion from principals in reporting them.

Whether the problem really is any worse today remains debatable, although observers say an upswing in violence in schools would be no surprise considering the city's escalating homicide rate and violence.

District numbers show a 4 percent increase in assaults on teachers and administrators this school year, many of them committed by children in kindergarten through fourth grade.

On average last school year, three or four of the district's more than 11,000 teachers and administrators were assaulted on any given school day.

Philadelphia has had a slightly higher victimization rate than the national average for urban districts. In 2003-04, 5.5 percent of urban public school teachers reported being assaulted, compared with 8 percent in Philadelphia that year.

Numbers aside, Burd's case stands out for its severity. District veterans called Burd's life-threatening injury the worst case of violence against a teacher in decades. The news of the attack on Burd prompted West Philadelphia High School teacher Ed Klein to go public 10 days ago about a November assault that broke his jaw.

"People were so stunned. It reminded us that we haven't solved our problems yet, that we still have incredible problems," Paul Vallas, the district's chief executive officer, acknowledged in an interview Friday.

Assaults on teachers, though rarely serious, have plagued the district for years, drawing public attention only when a particularly egregious attack or series of attacks occurred.

Six years ago: A second grader threatened to bring in a shotgun and kill his teacher. A high school teacher was out on workers' compensation for months after being jumped from behind, punched and kicked while trying to break up a fight. A chair was thrown at a middle school teacher, and weeks later she was threatened by the same student, who said she would pour gasoline on her and set her afire.

All these were reported in a front-page Inquirer article about teacher assaults.

Since that 2000-01 school year, the number of assaults on teachers and administrators has fluctuated.

District numbers show an uptick in 2002-03 and 2003-04 after Vallas instituted a "zero tolerance" discipline policy with sanctions for principals if they failed to report incidents. Reports of incidents peaked in 2003-04 at 1,024.

This school year, out of the more than 270 district schools, 22 have reported five or more assaults on educators.

Among them is West Philadelphia High School, which erupted last week after the principal was removed amid staff assaults. Teachers complained they were pushed, punched, slapped and threatened, sometimes without consequences for students. Of the 14 assaults reported there by Jan. 31, Klein's was the most serious.