How Much of Costs of Specialized Teaching

Division of labor has worked wonders for the production of clothing and computers. It doesn’t have the same transformational effect on productivity in teaching.

Teacher specialization, a model in which teachers specialize in certain subjects and teach them to a rotating group of students, has a negative effect on student scores, attendance, and behavior in an elementary school setting, according to a new working paper by Fryer, a faculty member at the Harvard Graduate School of Education.

Why? Specialization does have benefits: It gives teachers more time to prepare lessons and lets them teach subjects with which they are more comfortable. But specialization also has costs: It gives teachers fewer opportunities to tailor pedagogy to individual students and to follow through on behavior coaching.

For elementary school teachers, in-depth knowledge of specific subjects might not be as valuable as in-depth knowledge of individual students.


Fryer’s study, published by the National Bureau of Economic Research, describes a two-year, randomized field experiment in grades three, four, and five at 50 traditional public schools in Houston. The study split the schools into two groups of 25; in one group schools maintained their original system of one teacher per class; in the other, principals reorganized the school day so that teachers taught one or two of their strongest subjects to multiple classes.

In the schools in that latter group, students stayed with the same class all day; only the teacher changed. Depending on how many teachers there were per grade, each taught either math, reading, science and social studies, math and science, or reading and social studies.

To gather data, Fryer compared students’ reading and math scores from the three years leading up to the experiment to scores in the two years of the experiment. The results, he writes, “are surprisingly inconsistent with the positive effects of division of labor typically known to economists.”

  • Students with multiple teachers scored, on average, slightly lower in both math and reading relative to students with one teacher. Special education students with more than one teacher did even worse, as did students taught by inexperienced teachers.
  • Specialization also negatively affected behavior and attendance.
  • A teacher survey revealed that teachers in those schools were significantly less likely to report that they provided tailored instruction for their students.


Why the negative effects? Fryer and his research team offer several possible reasons.

First of all, as Fryer writes, “Production of human capital is far more complex than assembling automobiles.” These results add to evidence that boosting student achievement has few simple fixes — particularly in a school district like Houston, in which 88 percent of students are black or Hispanic, about 30 percent have limited English proficiency, and about 80 percent are eligible for free or reduced-price lunch.

Teacher specialization also usually means that students move classrooms throughout the day (even if they stay with the same class of students), and these constant transitions can decrease instructional time.

Mostly, the findings suggest that teaching elementary school requires a different type of specialization than the one examined in this experiment. It seems that for a young child, it’s important to have a single teacher who knows that child well enough to customize teaching to his or her needs, who spends enough time with students to be able to understand and respond to their behavior, and who has few enough students to focus energy on building relationships with them.