After a talented co-worker left their “dysfuctional” Brooklyn public school to work at a charter school, he told Ariel Sacks:

I didn’t fully realize it before, but all the craziness that was constantly going on around me was clouding my teaching. With all of that gone, I can identify my weak points and improve on them.

Sacks ponders what that “craziness” looks like — computers that don’t work and no money to pay a technician, chronic absenteeism among students — and how it forces teachers to plan for unexpected obstacles. What does it mean to compare teacher effectiveness in such different environments, she asks:

Teachers at schools like mine get used the multitude of x factors. In fact, we stop expecting everything to be “just so” and start going out of our way to plan for all of the unexpected things that might happen. Does this make us less effective? Maybe it does, in a way. It is harder to address problems quickly and effectively, when new problems present themselves simultaneously. But is it fair to call us less effective? Is it actually fair to measure my effectiveness in the same way my former colleague’s teaching is now measured, when the playing field is not level? Is the job of teaching in these very disparate environments even the same?

If the quality of my teaching is measured by my students’ scores on the same test that Joe’s students also take, and soon, I am compensated based on this same determination, then tell me—why should I keep on working at a school that can’t provide me everything I need to reach my full potential as a teacher?