A few years ago, after more than 20 years of full-time college teaching, I taught a course on survey research methods for the first time. Was I a novice teacher? Not at all, from the standpoint of having taught well over a thousand students and around 75 courses over that period. Yes, certainly, in the sense that I was teaching this subject matter at this level for the very first time. Some of what I had learned from my teaching experience, such as how to organize a class, or assess student learning—what we might call general pedagogical knowledge—would readily transfer to this new teaching setting. And I felt that I knew the subject matter of the course quite well. But I was still a novice in discerning which course topics students might struggle with, or what the best way to present a particular topic might be—what Lee Shulman and others have called “pedagogical content knowledge.” The next time I taught the course, I felt that the experience gleaned from the first time around gave me much more insight into how to sequence the material, which topics needed additional time to master, and when an informal explanation was more useful than a technical one.
If my teaching experience at the time I first taught this class were being gauged by administrative records, or a paper-and-pencil survey, it’s very likely that I would have been recorded as having more than 20 years of experience. And yet I was a novice at teaching this subject at this level of schooling. We might get a different picture of the distribution of teaching experience in a population of teachers if we looked at how much experience a teacher has teaching a particular subject—e.g., math, or reading—at a particular grade level—e.g., second grade, or sixth grade.
There’s some recent evidence on this in the technical report for the Teacher Data Initiative, the NYC Department of Education’s effort to generate a value-added measure for individual teachers’ contributions to their students’ performance on the state math and ELA exams. The technical report shows the distribution of years of teaching overall for fifth-grade teachers in New York City, as well as the distribution of the number of years of experience teaching math at the fifth-grade level and reading at the fifth-grade level. I wouldn’t place too much stock in the precise numbers for experience teaching a particular subject at the fifth-grade level, as they were produced specifically for the Teacher Data Initiative from teacher course-assignment data from 2000-01 to 2007-08, and these course-assignment data are a work in progress. In contrast, the overall years of teaching experience are from the DOE’s human resources records. There are experience data for 95% of the teachers.
Figure 1 below shows the distribution of experience for the 2,800 fifth-grade teachers who taught students in math in 2007-08. Overall, about 7% of these teachers were in their first year of teaching in NYC. But 27% of them were teaching fifth-grade math for the first time. About 15% of these teachers were in their first or second years of teaching in NYC, but 47% of them were in their first or second years of teaching fifth-grade math. On average, New York City has a highly-experienced fifth-grade teaching force, with well over 60% of the teachers having taught in NYC for at least five years. But only 22% of these fifth-grade teachers have taught fifth-grade math for five or more years.

The story is similar for the distribution of fifth-grade teachers teaching English Language Arts in 2007-08. Figure 2 below shows that about 29% of the fifth-grade teachers in 2007-08 were teaching ELA at the fifth-grade level for the first time in that year, and that 50% were in their first or second years of teaching fifth-grade ELA. As was true in Figure 1, however, only about 15% of these teachers were in their first or second years of teaching in New York City. Only 17% of the fifth-grade teachers teaching ELA in 2007-08 had five or more years of experience teaching fifth-grade reading.
Bottom line: Overall teaching experience and experience teaching a particular subject at a particular grade level are not the same thing. We need to better understand the forces that result in teachers shifting the subjects and grade levels they teach.
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