“How’s your teacher?”: Trying to define teacher quality
What makes an effective teacher? We all know one. But ask us to describe a good teacher’s qualities, and the answer is likely a vague “You know it when you see it.”
The same dilemma occurs in teacher quality research. Through things like Tennessee’s value-added scores, we can tell when an effective teacher is in the classroom when we see his or her effects on students’ learning. Scores rise, and especially for poor and minority children, the positive impact can be dramatic.
What we don’t know is exactly what makes that teacher effective. Any one single indicator of teacher quality— for instance, something like years of experience—rarely yields a strong correlation. But recent research has given more insight into whether the characteristics we’ve been requiring have any correlation, and what combinations of characteristics seem to reliably predict a quality teacher.
State certification: Some types
Research suggests that traditional certification might matter. Studies have found that subject-area certification in mathematics for secondary teachers is associated with higher student math performance (Goe 2007, Clotfelter et al 2007). But the findings are often mixed, with some studies showing little or no difference on elementary students’ performance (Gordon et al 2006).
Evidence on alternative certification is mixed, partially because there are at least 140 different types of programs throughout the country. Teach for America, the most visible of these programs, has been studied extensively, with newer studies being more positive about the program’s effect (Xu, Hannaway, and Taylor 2007).
The research is clear on one aspect: Putting teachers with emergency or no certification has, on average, a negative effect on student achievement (Goe 2007, Darling-Hammond et al 2005).
Subject-matter knowledge: Maybe
It seems intuitive that teachers need to be well-versed in the subjects they teach. But the research has found that the picture is more complex. Some studies have shown a correlation between teachers having a major in math and their students’ math achievement. But in other subjects, little relationship has been established between teachers’ subject-matter background and student achievement.
Advanced degrees: No
Most district policies and collective-bargaining agreements assume that teachers with master’s degrees and doctorates are more effective than those with bachelor’s degrees. However, recent studies have produced evidence that advanced degrees are not associated with more effective teachers. In fact, in many cases recent studies have found a negative effect (Clotfelter, Ladd, and Vigdor 2006).
Academic qualifications: Yes
A clearer way of looking at the whole field of teachers’ academic background may be to look at the rigor of the programs they complete and their achievement, for there is evidence that teachers’ academic qualifications are associated with effectiveness. Students whose teachers have higher math SAT scores have higher math achievement; so, too, do students whose teachers attended a more competitive college, although less so (Boyd et al 2007). Higher scores on teacher licensing tests are also associated with higher levels of student achievement, particularly in math (Clotfelter, Ladd and Wigdor 2007).
As with any profession, teachers benefit from experience. The evidence shows, though, that experience matters only up to a point. Most of the gains from experience occur in the first four years of teaching (Rockoff 2004; Rivkin, Hanushek and Kain 2005; Kane, Rockoff and Staiger 2006). It is unclear whether this plateau effect reflects the possibility that experience yields little benefit after the first few years, or that the more able teachers leave the profession after that time.
How good teachers are distributed
Whatever measures you use to define a good teacher, high-poverty schools and minority students are less likely to have those teachers. For instance, black and Hispanic students are twice as likely as white students to be taught by out-of-field teachers (Education Trust 2008). Or take the fact that in New York City, 35 percent of teachers in high-poverty schools had failed the state licensure exam on their first try (Boyd et al 2007).
Schools should pursue a combination of characteristics
A study of teachers in New York City suggests that a combination of characteristics makes a substantial difference. Teachers who were certified and who had stronger academic qualifications (as described in the above section) were more effective in the classroom, reducing the achievement gap between low- and high-poverty students by almost a fourth (Boyd et al 2007). Districts that are seeking to raise achievement should consider seeking teachers with the observable characteristics that are associated with effectiveness: Certification, academic credentials, and experience. In addition, districts might consider consciously placing teachers who are likely to be effective in schools with low-income and minority students.