Jay Mathews, the conservative foil to Valerie Strauss at the Washington Post, admits he likes Value Added Measures (VAM) in theory, but concedes that the reform is misused and abused and likens it to an action film monster that must be destroyed.
The “best” criticisms he has seen came from teacher trainer Grant Wiggins who points out that VAM “models accurately predict over a three-year period, performance at the extremes.”
In other words, if you average VAM scores over three years, you can identify the really great teachers and the really lousy ones.
Assuming this is true, the vast majority of teachers—who fall somewhere in the middle—would be getting inaccurate VAM scores and potentially bad evaluations as a result. Furthermore, because most school districts that use VAM are using them to evaluate teachers on a yearly or biyearly basis, even those falling at the extremes may be getting inaccurate VAM scores. Thus, no one is being accurately assessed by VAM.
While this is a compelling argument against VAM, there are a host of other compelling criticisms.
One of the assumptions of VAM is that a good teacher can help low income students improve as much as higher income students. This is not necessarily the case. Wealth does not simply cause students to earn higher test scores, but provides a variety of advantages that benefit affluent students throughout their lifetimes, including better health, greater access to enriching extracurricular activities, and a significantly lower risk of low birth weight, malnutrition and environmentally-induced illnesses. This decreases the chances that an affluent child will develop learning disabilities or impaired cognitive development and may increase how quickly they can learn and how much of the learning is retained. In other words, teachers at affluent schools may see greater gains in student learning because of their students’ socioeconomic backgrounds.
How much a student improves from year to year is also dependent to some extent on their previous teachers. For example, a chemistry student who had a bad math or science teacher the previous year may be lacking so much of the prerequisite knowledge and skills that their growth in chemistry is severely limited.
What Does it Mean to Be a “Really Good” Teacher?
Most would argue that there are certain easy to identify practices that characterize a “good teacher” like having a strong background in the content, creative and effective lesson design, good classroom management and a positive rapport with students.
While any teacher who has these qualities ought to be considered a “good teacher,” in reality the teachers identified by administrators as “great teachers” are often the ones who come in at 6 or 7 and stay until 6 or 7. They may in fact be excellent teachers, too, or their VAM could be a reflection of how many extra unpaid hours they are putting in.
Some would likely argue that this is a legitimate use of VAM: A teacher who puts in long hours for her students and gets them to perform better deserves a good evaluation, promotion, bonus pay, etc. However, it is not fair or reasonable to evaluate teachers on whether or not she puts in unpaid volunteer time over and beyond that required by her contract. Under this scenario, an excellent teacher who works the contractual hours or, as most of us do, who works more than the contractual hours, might still get a lower VAM score than a martyr who puts in 70-80 hour weeks.
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