Very Interesting article on the man who created the Value Added Model for evaluating teachers.
To fairly evaluate teachers, Mr. Sanders argued, the state needed to calculate an expected growth trajectory for each student in each subject, based on past test performance, then compare those predictions with their actual growth. Outside-of-school factors like talent, wealth and home life were thus baked into each student’s expected growth. Teachers whose students’ scores consistently grew more than expected were achieving unusually high levels of “value-added.” Those, Mr. Sanders declared, were the best teachers. . . .
Schools were collectively spending billions to give teachers with master’s degrees extra pay. Yet their value-added bell curve looked little different from the curve for teachers without those degrees. Nor did effectiveness grow in lock step with years of service. . . .
Up until his death, Mr. Sanders never tired of pointing out that none of the critiques refuted the central insight of the value-added bell curve: Some teachers are much better than others, for reasons that conventional measures can’t explain. His system is still used in Tennessee today. In the last dozen years or so, the state’s scores on federal N.A.E.P. exams have improved faster than those of the average state. . . .
His data were, he believed, inherently pro-teacher. Kati Haycock, founder of the education civil rights group the Education Trust, says that Mr. Sanders’s work revealed that teacher effectiveness “makes a huge difference in the trajectories and life chances of different kids.”
While the use of value-added ratings to hire, fire and pay teachers may have been limited by political pressure, the importance of the value-added bell curve itself continues to grow — less like a sudden explosion than a chime whose resonance gains in power over time. The questions that occupy lawmakers and administrators today are not whether to identify the most and least effective teachers, but how.