Well, there goes the idea that good educators have kept their jobs in D.C. Public Schools:

Headlines about D.C. school reform efforts have often involved the firing of teachers who scored poorly on the IMPACT evaluation system adopted in 2009 — about 300 in the past two years. But the District has also shed 145 teachers, including counselors, deemed effective or even highly effective. These employees lost their jobs through a process known as “excessing.”

Reasons for excessing vary from school to school, with principals making the final call. They include budget cuts, rising teacher salaries, enrollment declines, changes in academic programs and staff overhauls mandated under federal law.

About 70 percent of the 522 teachers excessed since 2010 found other jobs in the system, school officials report. Washington Teachers’ Union President Nathan Saunders said schools can ill afford to lose any effective educators. He contends that a push for younger, lower-cost hires — some recruited from programs such as Teach for America and D.C. Teaching Fellows — has wrongfully forced out seasoned practitioners.

Though Chancellor of Schools Kaya Henderson says most of the teachers let go are in “specialized” fields where there isn’t great demand, records suggest that DCPS actually is just hiring inexperienced, cheaper teachers to replace the older ones pulling down higher pay.