Now it is teachers in Ohio that have been rated by a secret value-added formula.

Teachers in affluent schools were twice as likely to score well as those in low-income schools.

Here is the key language:

“The details of how the scores are calculated aren’t public. The Ohio Department of Education will pay a North Carolina-based company, SAS Institute Inc., $2.3 million this year to do value-added calculations for teachers and schools. The company has released some information on its value-added model but declined to release key details about how Ohio teachers’ value-added scores are calculated.

“The Education Department doesn’t have a copy of the full model and data rules either.

“The department’s top research official, Matt Cohen, acknowledged that he can’t explain the details of exactly how Ohio’s value-added model works. He said that’s not a problem.”

Think of it. The person at the Ohio Department of Education in charge of the ratings doesn’t understand how the model works. He says it is not a problem.

Well, it is a problem for excellent teachers who were told they were “least effective.”

These models,based on standardized tests, are inaccurate and unstable.

Do not trust the ratings. They are garbage. No high-performing nation is rating teachers this way. It is mean-spirited, mechanistic, and meaningless.