Don't Grade Teachers With a Bad Algorithm

For more than a decade, a glitchy and unaccountable algorithm has been making life difficult for America's teachers. The good news is that its reign of terror might finally be drawing to a close.

I first became acquainted with the Value-Added Model in 2011, when a friend of mine, a high school principal in Brooklyn, told me that a complex mathematical system was being used to assess her teachers -- and to help decide such important matters as tenure. I offered to explain the formula to her if she could get it. She said she had tried, but had been told “it’s math, you wouldn’t understand it.”