Teacher effectiveness and student test scores

Last week-end I met an Ohio teacher named Judy who works with elementary-aged, struggling readers. I asked Judy where she taught and, as she told me, she couldn’t help sharing her intense frustration with Ohio’s system for evaluating teachers which, according to her, relies heavily on test scores. She felt this system extremely unfair to her since, almost by definition, the students she worked with will make only limited progress over the course of a school year. The pressures of these accountability measures were clearly robbing Judy of the pleasures of teaching.

Implicit in NCTQ’s assertion that university-based teacher prep programs aren’t adequately preparing teachers to teach reading is the claim that teachers are generally unprepared for the rigors of teaching. The sense that many teachers aren’t up to the task is behind the spread of teacher evaluation schemes that Judy found so stressful and unfair. Most of these teacher evaluation systems rely on student test scores which may seem logical but, as it happens, student test scores are not a fair or principled way to evaluate teachers. There are at least a couple of reasons for this. First of all – and this may come as a surprise to many people – research indicates that teachers are NOT the most significant influence on academic achievement. According to Berliner and Glass (2014), most research indicates that less than 30% of a student’s academic success is attributable to schools, and teachers are only part of the overall school effect, perhaps not even the most important part. Other factors, particularly the material effects of poverty, account for over 60% of the variance that can be accounted for in student achievement (Berliner & Glass, 2014). Another problem with using test scores to measure teacher effectiveness is that these measures tend not to be very reliable. Teachers whose students do very well one year often do not do well the following year (Berliner and Glass, 2014), not a surprising finding given the influence of non-school factors in student achievement.  

I am not arguing that teachers should not be evaluated. Far from it. But teacher evaluation schemes based on test scores are unfair, unreliable and ineffective. And they make a difficult job – teaching – even more difficult.