The novelist Philip Roth never forgot his high school homeroom teacher, as his eulogy reveals ("In Memory of a Friend, Teacher and Mentor," The New York Times, Apr. 20). But it's a telling commentary that the words of a celebrity are needed to remind us what the accountability movement is missing in overwhelmingly relying on quantification to evaluate teachers. The value-added metric, for example, demands evidence in the form of observable cognitive changes in students from one year to the next. But what about affective changes in the same time period, or more importantly in the long run?

Lorraine Bellon Cella's essay addresses this oversight ("How Do You Evaluate Teachers Who Change Lives?" Education Week, Apr. 16). She correctly understands what reformers don't: Teachers often leave an indelible imprint on their students in ways not necessarily reflected in the tests in widespread use. The most influential figures in my life beside my parents were my teachers. I recognized their importance when I was in their class in some cases. But it took years later in other cases to fully appreciate what they did for me.

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