Could a brutal assault on a Spingarn high school math teacher by a special needs student last month been avoided if the instructor had access to more of the student’s history? That’s what the Washington Teachers’ Union is arguing in a letter to Chancellor Kaya Henderson.

D.C. school officials confirmed that the incident took place about 1 p.m. May 5, when a 16-year-old student attacked a teacher. In his letter to Henderson, WTU president Nathan Saunders said the student had recently been transferred to Spingarn from The Pines Residential Treatment Program in Portsmouth, Va. Saunders provides some alarming details:

“Once in the Spingarn teacher’s class, the teacher asked the student to be quiet, at which time, and without further provocation, the student attacked the teacher. The attack caused injuries so severe that the teacher had to be hospitalized and will likely need reconstructive surgery to repair the damage done to her face. Nearby students in the class had to restrain the student in order to end the vicious attack.”

Saunders said the incident raises a broader concern: with the District committed to reducing the number of special needs students served in private facilities at public expense, teachers need to be advised and better prepared for new arrivals that may have violence in their backgrounds.

“Many other students with propensities for violence have been transferred to D.C. Schools without notification to the teachers with whom the students are entrusted,” Saunders wrote.

Records show that in fiscal year 2010, 118 District students were treated at The Pines, at a cost of $1.6 million. In the current fiscal year, that number is down to 55, at a cost (as of this spring) of $325,000. This is not meant to suggest that every student coming out of The Pines is potentially violent, but only to show that the city is bent on bringing the numbers down.

Saunders said he understood that privacy is an issue, but that “failure to disclose such vital information is unnecessary and puts the safety of students and teachers at risk.” He called for a review of the city’s effort to reintegrate special needs students, “including an assessment of whether the necessary supervision and care is being provided in their new setting.”

Henderson, reached by e-mail this morning, declined to comment on the specifics of Saunders’s June 9 letter. She said only: “We are preparing a response.”