Justin, a middle school math teacher, shared his concerns about DDMs with me this week. I asked why he is supporting his district’s purchase of an off-the-shelf product to measure student growth.

Me: Why not create a DDM to measure what you care about, like the math practice standards from the Common Core?
Justin: I worry about the consequences of creating a DDM without a high level of validity and reliability.
Me: If your students’ growth ends up being low due to a flawed measure, won’t you be able to explain that to your evaluator?
Justin: Yes, with my current evaluator– but what if that person goes elsewhere? How can I be sure that his replacement will be equally understanding and trustworthy? And, if I am given a low impact rating, might it become difficult to get a job in another district?

And therein lies the nature of the minefield. Yes, the results of a low impact rating are not huge– moving from a two-year self-directed educator plan to a one-year plan– but what hard-working, caring teacher wants to be unfairly tagged with a low rating? And the long range impact on a teacher’s ability to find a new job may be immense.

What’s to be done? In my next post I’ll propose some of the long range benefits to be gained from implementing DDMs.