Teacher Quality First

The inestimable Joanne Jacobs points us to a story appearing in the New York Daily news that makes a similar argument I made many months ago, that smaller classes sizes is not a solution unless you can find enough quality teachers to make smaller class sizes better. From Andrew Rotherham

Common sense and research both tell us that if all else is equal, smaller classes are good for students. Unfortunately, in urban education, all else is rarely equal, and a host of problems hinder efforts to attract top teachers. So reducing class size without addressing teacher quality more broadly is akin to continually adding pitchers to your bullpen without worrying about whether any of them can even throw a fastball.

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Research is clear that good teachers matter more than small classes, and all of these problems are substantial obstacles to attracting and retaining top teachers. To get the most bang for the buck, teacher quality rather than quantity should be New York City's top priority right now.

That is the catch that teachers unions and smaller class size proponents fail to understand or perhaps fail to acknowledge. Smaller class sizes have not actually improved the education of children because we cannot, even on a micro scale, adequately ensure high quality teachers to teach those students.

Last October I argued, with some mathematical examples, that bigger class sizes are better because larger classes actually reduce the demand for teachers, allowing school systems to pay better and cull the cream of the teaching crop. Here is what I wrote:

The larger the class size, the fewer teachers that need to be hired. A fairly obvious statement. Concurrently with the idea of fewer teachers needing to be hired is that, in a perfect model, a school system can hire more teachers with a desired level of quality.

The definition of teacher quality is irrelevant in this model. No matter how a community defines a quality teacher, usually an amalgamation of education, experience, professionalism, and personal attributes, quality can be placed on a bell curve ranging from 1 (the poorest quality) to 100 (the highest quality). The peak of the curve would be about 75. Assuming you have a large enough population of potential teachers, all teachers would fall onto that curve.

If you must populate your school districts teacher population from people on that curve, you obviously seek to attract the highest quality--those at the upper end of the curve. However, the number of high quality teachers, defined as those with a quality score of 85 or better is finite and usually will not suffice to adequate man you schools. Thus, the more teachers you need, the lower the quality score you have to accept as teachers.

If your desired quality score for teachers is 80, there are far more potential teachers with a quality score below 80. If you have a school district of 10,000 students and a desired student teacher ration of 20:1, you have to fill 500 teacher positions. If your potential teacher pool is 1500, statistically, only 150 teachers would have a quality score of 90 or better and another 200 with a quality score of 80-90. You can then hire 350 teachers of desired quality, but still have to hire 150 teachers with less than desired quality. However, if you find that a desired student teacher ration is 25:1, then you have to hire 400 teachers of which only 50 are of less then desired quality. Finally, if you think 30:1 is a workable ratio, you need only hire 334 teachers--which means that all teachers are of the desired quality.

Thus, if school districts focused on quality teachers instead of the number of students they are required to teach, you can develop a higher quality teaching corps and thus improve education for all students, not just those students in smaller classes who luck into a quality teacher.