As Dana Goldstein explains in The Test Generation, it' not hard to identify the least effective teachers. Test score-driven evaluation can kill two birds with one stone, however, by getting rid of the worst performers as well as veteran teachers who are not on board with education's brave new world. Goldstein reports that the Harrison District in Colorado has removed 1/3rd of teachers in the bottom two categories of effectiveness. That comes out to 4% of the teaching force. The district lost 11% of it top performers. It also loses 25 days to "high-stress testing." Their teacher attrition rate is the
