A high school teacher in New York sent me the following e-mail, which discusses a most unfortunate unintended consequence of the state's new teacher and principal evaluation that depends largely on how well students do on standardized test scores.

The “value-added” method of evaluation — which uses complicated formulas to determine how much “value” an educator has added to a student’s achievement on a standardized test — is now the law in New York as well as a host of other states. New York’s system is known as the APPR,or Annual Professional Performance Review.

Many assessment experts have warned that such evaluations are unreliable, but school reformers have insisted on implementing these systems anyway. This has occurred even though there are school systems that have effective teacher evaluation systems that don’t use standardized test results, including in high-achieving Montgomery County in Maryland and Fairfax County in Virginia.

This teacher raises an important consequence of putting high stakes ona standardized test.

Here’s the e-mail:

“With testing so much in the news, I thought I would drop a quick note to tell you about a recent occurrence here in my district. A math teacher who teaches Trigonometry, a class for which there is a state Regents exam, pointed out the following trap for teachers.

He has some students in Trig who wanted to take the class to challenge themselves, but may not do very well on the Regents exam. Most of these students don’t need to pass the exam to graduate as they have fulfilled their math requirements already.

So, some of them may decide to blow off the exam, though they still have to take it because it is the final exam for the course; others may give their best effort on the exam to see how well they can do, but may not score very well. Yet all of these scores are going to be used to judge the teacher as part of his APPR score here in New York.

So, the teachers now have an incentive to prevent students from challenging themselves and trying higher level math. After all, if they challenge themselves but don’t do well on the exam, it hurts the teacher more than the student.

The higher the stakes of the test the more the testing becomes a deterrent to learning.”