Bill & Melinda Gates Foundation

From Sophistry to Science: The Importance of Class Size

June 05, 2013

For a counterpoint to this post, check out "One Class Size Does Not Fit All."

In a recent online commentary in the New York Times opinion pages, Sara Mosle began with question “Does Class Size Count?” The dispute continues between those who contend that the expertise of the educator in the classroom is of greater importance to realizing improved academic achievement than is the number of students in the class.

At staff meetings around the nation - as some back-handed compliment, one must suppose - administrators are informing educators that they would rather place forty-five children in a room with one great teacher rather than divide the children between two less-skilled performers.

Virtually all of us have known a couple such instructors in our lifetimes. Occasionally, teachers are able to overcome challenging circumstances. Statistically, however, these “natural” pedagogues are outliers on the bell-curve of practitioners. Questions of sustainability should leap immediately to mind when such proposals are seriously considered.

 Our national quest to optimize learning outcomes for children will eventually require that all teachers serve a more reasonable number of clients, especially in schools that serve the socio-economically disadvantaged.

How long will those gifted instructors be able to sustain the effort required to advance larger numbers of children academically? Do we have adequate resources to deliver differentiated compensation for the increased workload both "on-stage" and "off-stage"? What guarantees the fidelity of the instructional program when those teachers retire or simply leave the profession due to stress and/or fatigue?

Some years ago, the state of Maryland simply codified in collective-bargaining law that "class size is not a working condition, and, therefore, not subject to bargaining.”  That sentence has been repeated so frequently that most simply accept it without question.  However, for educators, this decision constitutes little more than a political decision based on specious legal reasoning. Fiduciary concerns were the deciding factor. Fidelity to concerns about instructional objectives and academic outcomes for all students did not inspire the ruling.

To render a decision based on the real needs of children, consulting the laws of physics might serve as a more secure foundation for education policy: The Second Law of Thermodynamics comes immediately to mind.

For every physical system in the Universe, the tendency of physical systems is to devolve toward disorder. The probability of arriving at total disorder, or chaos, increases exponentially as the number of elements in the set increases. The measure of that tendency to move toward disorder is called entropy; the higher the number of elements in the set, the greater the entropy.

Throw forty unbound pages in the air, there is one way to land “in order”, there are 4040 ways to land in disorder. Now imagine performing the same experiment with 400 pages.

This law applies to every physical system in the observable Universe. Why would anyone suppose that it has no application in a classroom?

When an instructor walks into an “ideal” class of fifteen students, the possibility of the system moving toward disorder is, at least, 1515, assuming that each student represents just one variable. More likely, though, is the likelihood that each student truly represents a whole host of variables that further complicate the calculation of possible interactions and the striving of the system to achieve a disordered state.

 Even “modeling” at these comparatively small numbers, is it not impressive that most teachers are able to enter a classroom and impose order in the pursuit of transferring knowledge to children?

However, too many teachers still confront daily realities doubling, tripling and sometimes even quadrupling that “ideal” class size. In these situations, teachers endure potential measures of entropy that approach absolute certainty. Can we even formulate a compensation model for classroom instructors that walk into a scenario where the likelihood of "disorder" is based on 3535 interactions? Are there really any pedagogical methodologies that will ensure the success of every student when 4545 interactions, or more, are possible in the classroom? Can this society really tolerate that students-with-the-greatest-needs are warehoused in classrooms with 6060 possible interactions to distract from learning?

Our national quest to optimize learning outcomes for children will eventually require that all teachers serve a more reasonable number of clients, especially in schools that serve the socio-economically disadvantaged. We can no longer afford to pretend that teaching a few affluent students is the same job as teaching many impoverished ones. It simply defies logic to assume that “individualizing instruction” for large classes does not consume more time. The question, as always, remains: “How does a community muster the political will to achieve more equitable opportunities to learn for all children?”

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