A Value Added Approach to Teacher Performance

My wife, Holly, spent 4 years as a public high school English teacher in California.  From time to time, she would tell me about the "evaluations" she had coming up, which would consist of a senior teacher or administrator (usually her principal) sitting in on a lesson and giving her feedback about both the content of the lesson and some peripheral items, like how she managed her classroom.  While I don't doubt the necessity of these sorts of evaluations, especially for teachers in their first few years on the job, I couldn't help but wonder why there weren't any good, objective measures of teacher performance in place.

Every year, elementary, junior high, and high school students take standardized tests across a broad range of subjects.  Most importantly, they are tested against state-wide benchmarks for basic quantitative and language skills.  Students are graded on a relative basis, so a student placed in the 50th percentile is approximately average.  Changes in these percentile scores over time could provide and objective way to measure teacher performance.

For instance, let us imagine that an English teacher begins the year with a class of 20 freshman who scored, on average, in the 70th percentile on the previous year's standardized English test.  The material on the new year's test will be more advanced, but the average teacher should be able to maintain student scores in the 70th percentile.  A less talented teacher will cause those scores to drop, while a more talented teacher will cause those scores to rise.

While this idea alone could form the core of an objective, fully automated way to track teacher performance, there are still some rough edges that would have to be ironed out.  The most obvious is that is is likely much more difficult to help a student from the 98th to the 99th percentile than it is to help a student from the 50th to the 51st.  If teachers were evaluated solely on the absolute improvement they generated, teachers who inherited already stellar performers would be at a severe disadvantage in relation to those inheriting mediocre performers.

Fortunately, a basic solution to this problem is not too difficult to imagine.  All that would be necessary is to create a scale defining equivalent values for improvements from certain levels.  For instance, it may be determined that moving a student from the 70th to the 75th percentile is equivalent in value to moving a student from the 95th to the 96th.

Ultimately, it may not even be necessary to solve the problem.  It may be that some teachers work best with students in certain percentile brackets.  A performance evaluation system like the one I've described would provide the information necessary to identify the teachers and instructors that are best equipped to handle students at various aptitude levels.  I expect parents would find this information an invaluable resource as they work to provide the best education for their children.