Sep 11, 2012 at 8:10 am
Steve Greenhouse does a nice job of explaining what’s going on in this high visibility strike by Chicago’s public school teachers. I need to learn more about the details before I develop my own view, but two things to keep in mind here.
First, public opinion turns out to be very important in these high visibility cases, and given today’s climate facing public sector unions, and teachers’ unions in particular, one should worry a lot about balance in how this action gets treated in the media. (I was reminded of what may have been the most ridiculous line from the RNC a few weeks ago, from Gov Christie: “Democrats believe in teachers’ unions; we believe in teachers.”)
Second, note this line from the NYT article (my bold):
Eager to improve Chicago’s schools, [Mayor] Emanuel has taken several steps — among them pressing the school board to rescind a promised 4 percent raise — and made numerous demands that have infuriated the Chicago Teachers Union. He wants student test performance to count heavily in evaluating teachers for tenure, even though the union insists that is a highly unreliable way to assess teachers.
It’s not just unions. Rigorous academic work, some of it associated with my friend and Berkeley Prof Jesse Rothstein, has shown that such testing—using “value-added models,” or VAMs–is often a highly incomplete and unfair way to evaluate teacher performance.
VAMs are designed to isolate individual teachers’ value-added—new skills and knowledge acquired by students—from year-to-year. Often, as in the Chicago case, the results are then used for teacher promotion or demotion.
There’s nothing inherently wrong with that, assuming the tests are valid and reliable. But Jesse’s careful work has convinced me that they’re not, at least not yet.
Using VAMs for individual teacher evaluation is based on the belief that measured achievement gains for a specific teacher’s students reflect that teacher’s “effectiveness.” This attribution, however, assumes that student learning is measured well by a given test, is influenced by the teacher alone, and is independent from the growth of classmates and other aspects of the classroom context. None of these assumptions is well supported by current evidence.
Most importantly, research reveals that gains in student achievement are influenced by much more than any individual teacher. Others factors include:
• School factors such as class sizes, curriculum materials, instructional time, availability of specialists and tutors, and resources for learning (books, computers, science labs, and more);
• Home and community supports or challenges;
• Individual student needs and abilities, health, and attendance;
• Peer culture and achievement;
• Prior teachers and schooling, as well as other current teachers;
• Differential summer learning loss, which especially affects low-income children; and
• The specific tests used, which emphasize some kinds of learning and not others and which rarely measure achievement that is well above or below grade level.
However, value-added models don’t actually measure most of these factors. VAMs rely on statistical controls for past achievement to parse out the small portion of student gains that is due to other factors, of which the teacher is only one. As a consequence, researchers have documented a number of problems with VAM models as accurate measures of teachers’ effectiveness.
So, problem one is the VAM is not yet able to reliably isolate teacher performance amidst all these other factors.
Researchers have different views on the VAM problem but problem two is widely agreed upon, and it’s something I, and I suspect every other parent with kids in public schools, have seen first hand. People respond to incentives, and when their jobs are on the line, that amps up that incentive and response big time.
So you have teachers teaching to the test, even if the test is flawed and even if the test leaves out knowledge that the teacher (and parent) believes is essential to a child’s educational experience.
Again, my point is not that to endorse the Chicago teachers strike, though from what I can tell, they did not undertake it lightly. My point is that it’s not just “the unions” who object to having their members’ job performance judged on the basis of VAMs. In fact, their objections are founded on solid research.
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