Recently, Linda Darling-Hammond wrote a commentary piece about value-added evaluation methods for Education Week. Excerpts from her commentary are below:
Everyone agrees that teacher evaluation in the United States needs an overhaul. Although successful systems exist, most districts are not using approaches that help teachers improve or remove those who cannot improve in a timely way. Clearly, we need a change […]
However, previous experience is not promising. Recently evaluated experiments in Tennessee and New York did not improve achievement when teachers were evaluated and rewarded based on student test scores. In the District of Columbia, contrary to expectations, reading scores on national tests dropped and achievement gaps grew after a new test-based teacher-evaluation system was installed. In Portugal, a study of test-based merit pay attributed score declines to the negative effects of teacher competition, leading to less collaboration and sharing of knowledge.
I was once bullish on the idea of using “value-added methods” for assessing teacher effectiveness. I have since realized that these measures, while valuable for large-scale studies, are seriously flawed for evaluating individual teachers, and that rigorous, ongoing assessment by teaching experts serves everyone better. […]
Why?
First, test-score gains-even using very fancy value-added models-reflect much more than an individual teacher’s effort, including students’ health, home life, and school attendance, and schools’ class sizes, curriculum materials, and administrative supports, as well as the influence of other teachers, tutors, and specialists. These factors differ widely in rich and poor schools.
Second, teachers’ ratings are highly unstable: They differ substantially across classes, tests, and years. Teachers who rank at the bottom one year are more likely to rank above average the following year than to rate poorly again. The same holds true for teachers at the top. If the scores truly measured a teacher’s ability, these wild swings would not occur.
Third, teachers who rate highest on the low-level multiple-choice tests currently in use are often not those who raise scores on assessments of more-challenging learning. Pressure to teach to these fill-in-the-bubble tests will further reduce the focus on research, writing, and complex problem-solving, areas where students will need to compete with their peers in high-achieving countries.
But, most importantly, these test scores largely reflect whom a teacher teaches, not how well they teach. In particular, teachers show lower gains when they have large numbers of new English-learners and students with disabilities than when they teach other students. This is true even when statistical methods are used to “control” for student characteristics […]
Yet this has not stopped some policymakers in the United States from forging ahead. In Houston, where teachers are dismissed or rewarded based substantially on value-added scores, teachers can find little relationship between what they do and how they rate each year. As one put it: “I teach the same way every year. [My] first year got me pats on the back. [My] second year got me kicked in the backside. And for year three, my scores were off the charts. I got a huge bonus. What did I do differently? I have no clue.”
Among many teachers recently dismissed was a 10-year veteran who had been voted “teacher of the year.” Rated each year as “exceeding expectations,” she showed positive value-added scores in most subjects every year, except for the year she taught 4th grade, when English-language learners, or ELLs, are mainstreamed in Houston. The pattern of lower scores in classes with large numbers of ELLs is well known […]
So what’s the alternative? As in other professions, good evaluation starts with rigorous, ongoing assessment by experts who review teachers’ instruction based on professional standards. Evaluators look at classroom practice, plus evidence of student outcomes from classroom work and school or district assessments. Studies show that feedback from this kind of evaluation improves student achievement, because it helps teachers get better at what they do. Systems that that sponsor peer assistance and review programs also identify poor teachers, provide them intensive help, and effectively remove them if they don’t improve.
If we really want to improve teaching, we should look to such districts for models of effective evaluation, as well as to high-performing countries that have professionalized teaching by ensuring excellent preparation, on-the-job collaboration, and ongoing professional learning.
To read Darling-Hammond’s full commentary, please visit http://www.edweek.org/ew/articles/2012/03/05/24darlinghammond_ep.h31.html
