Grading Teachers

As budget deficits slam into public school districts across the nation, as the public demands that union-bargained, seniority-based tenure is no longer enough to lock in teachers to a safe haven of lifetime public employment – the anti-public union collective bargaining “Wisconsin effect” that is spreading nationwide – the issue of how to measure teacher performance has once again simmered to the surface. While unions may resist such evaluation methodologies, increasingly they are seeing that if they do not get involved in the process of determining how to grade teachers, they may just find such structures imposed upon them by pressed legislators and wary voters. The venue where America places its greatest trust – our system of public schools, charged with preparing our youth for life – is under attack.

The No Child Left Behind Act – with its standardized (state-by-state) testing structures and harsh penalties for failing schools – moved teachers from solid teaching towards “teaching to the test,” a subtle difference to many in the public, but one that has disheartened the best instructors with a “one size fits all” philosophy that almost everyone knowledgeable about public education admitted was seriously flawed. The application of replacement valuation parameters has almost everyone up in arms at some level, but methods are being applied nonetheless.

The March 28^th Los Angeles Times, in an article discussing how the Los Angeles Unified School District is grappling with a test matrix of value-added measurements, noted the resistance in other large school districts: “In Houston, school district officials introduced a test score-based evaluation system to determine teacher bonuses, then — in the face of massive protests — jettisoned the formula after one year to devise a better one… In New York, teachers union officials are fighting the public release of ratings for more than 12,000 teachers, arguing that the estimates can be drastically wrong.”

Although the task of assessing teachers’ performance in a variety of public school conditions – from a gang-invested inner city school to an over-equipped suburban facility where local families write supplemental checks to hire additional teachers and augment the cost of instruction – is most complex, there is an underlying value-added philosophy: “All value-added methods aim to estimate a teacher's effectiveness in raising students' standardized test scores. But there is no universal agreement on which formula can most accurately isolate a teacher's influence from other factors that affect student learning — and different formulas produce different results… [But there is no] widespread agreement about how much the resulting ratings should count. Tensions are all the greater because the stakes for teachers are high as more districts consider using the evolving science as a factor in hiring, firing, promotions, tenure and pay.

“‘It is too unreliable when you're talking about messing with someone's career,’ said Gayle Fallon, president of the Houston Federation of Teachers. She said many teachers don't understand the calculations. The general formula for the ‘linear mixed model’ used in her district is a string of symbols and letters more than 80 characters long: my = Xβ + Zv + ε where β is a p-by-1 vector of fixed effects; X is an n-by-p matrix; v is a q-by-1 vector of random effects; Z is an n-by-q matrix; E(v) = 0, Var(v) = G; E(ε) = 0, Var(ε) = R; Cov(v,ε) = 0. V = Var(y) = Var(y - Xβ) = Var(Zv + ε) = ZGZ^T + R.” LA Times. Oh that makes the test perfectly clear! Adding more variables makes the formula significantly more fair but even more impossible to understand, much less to explain to lay school boards where members have less than a PhD in math!

To underscore the unfairness of even these complicated parameters, Los Angeles schools’ chief, John Deasy, noted in the Times, that student poverty levels and environmental conditions definitely were mission critical: “Deasy said these were among the most difficult questions the district grappled with. Theoretically, value-added models inherently account for these differences, because each student's performance is compared each year with the same student's performance in the past, not with the work of other students. But many experts say further statistical adjustments are necessary to improve accuracy… A 2010 study of 3,500 students and 250 teachers in six Bay Area high schools by researchers at Stanford University and UC Berkeley found that, under their model, teachers with more African American and Latino students tended to receive lower value-added scores than those with more Asian students.”

Teachers and their unions are all over the map when it comes to how the relevant results can be applied. Some want it to be used for general informational purposes but not to impact a teacher’s career performance while others think it should be just one factor in a litany of other variables. Teachers and unions all seem to think that such mathematical calculations need to be balanced with other criteria, but as school districts face the need to lay-off teachers, the public seems reasonably concerned that those who remain are the best of the bunch. In recruiting the “best and the brightest” potential teachers now and in the future, we do need to be cognizant of not firing teachers because they have experience and hence are the most expensive in the batch – a serious deterrent to attracting instructors for the long term – while keeping in mind that quality is essential.

I’m Peter Dekom, and to this day, I still remember the names of the best public school teachers I had so very long ago.