D.C. Schools Chancellor Kaya Henderson today announced changes to the city’s teacher evaluation system, known as IMPACT. Her changes will broaden the measures by which D.C. public school teachers are rated and add a new category for those ratings.

Under the the current system, introduced by former chancellor Michelle Rhee, D.C. public school teachers are observed five times a year and rated. Those ratings—which run the gamut from “ineffective” to “highly effective”—determine if the teacher is given a hefty bonus (up to $25,000) or fired, much as 98 teachers were let go this week.

The changes introduced by Henderson will lower the reliance on student testing scores for rating teachers, increase the standards to be judged an “effective” teacher and add a “developing” category for those teachers who aren’t doing very well but still show potential:

Beginning this year, the minimum score required for an “Effective” rating has been raised from 250 to 300 on the 100-400 IMPACT scale. Today’s changes also include a new fifth rating, “Developing,” for teachers who earn final scores between 250 and 299. Teachers who earn Developing ratings will have three years to take advantage of the district’s professional development, including system wide school-based coaching, videos of exemplary practice, and a new program of content-specific support that will be provided to teachers in the system’s 40 lowest performing schools. Teachers who are still not meeting expectations after three years will be subject to separation from the system.

Broadening the measures of student achievement to rely less on testing is a big change. Earlier this year the Post reported on a fifth-grade teacher who was fired for low IMPACT scores, despite having been congratulated for having “motivated students and a positive learning environment.” Ultimately, it was her students’ test scores that did her in. Under the new changes, IMPACT will measure other variables so that teachers “receive credit for all of their instruction, not just the elements assessed on the state test,” said a press release.