If you think smaller class sizes are important to student learning, you should support expanding the number of charter public schools.

That’s the conclusion suggested by the most recent data available from the Michigan Department of Education, and it directly contradicts claims made by defenders of the conventional public school status quo, many of whom would rather limit or eliminate their charter school competition.

These anti-charter claims take various forms. For example, a recent study co-authored by a Michigan State University professor purports to find evidence for a common complaint of charter opponents, that charters here spend “substantially less on instruction” and “substantially more on administration” than conventional schools. The conclusion is spurious because the data it’s based on does not accurately reflect how charter schools spend their resources.

The proof is in the pudding: If charters allocated less to instruction they would likely have more students per instructor. Yet state government data for the 2010-2011 school year shows that charter schools had an average of 16.2 per instructional employee, vs. 18.5 in conventional schools. In the slightly narrower category of “classroom teachers,” charters had one for every 19.8 students, compared to 21.3 on average in conventional schools.

Likewise, if charters spent significantly more on administration, they would likely have more administrators per student. But again, the data show just the opposite: There were 87.9 students per full-time administrative staffer in Michigan charter schools on average, vs. 85.9 in conventional schools.

These are not very big differences, suggesting that charters and conventional districts are actually quite similar in their staffing levels for instruction and administration. In other categories however, charter schools demonstrate much greater efficiency.

For example, conventional districts employ far more noninstructional employees such as consultants, supervisors, coordinators, guidance counselors, janitors and bus drivers for a given number of students. Regular districts had one such noninstructional employee for every 28 students, while charters had just one for every 61 students. This disparity is exaggerated by the fact that few charters provide transportation, but that particular difference is unlikely to explain it away entirely.

The supposedly high levels of charter school administrative spending suggested by that recent MSU study and others like it are most likely due to different accounting procedures, not different spending priorities. For example, unlike regular districts, most charter schools lease rather than own their buildings and equipment, and post the lease expenses as “administrative” spending. An apples-to-apples comparison would count conventional school debt service payments on school infrastructure bonds as “administration,” which would skew this much higher.

In addition, charters contract out for many instructional support and other student services. These too may be posted as “administrative” expenses, when an apples-to-apples comparison would consider them related to “instruction” or “instructional support.”

Beyond all the complex accounting, unlike conventional schools, charter schools have a built-in incentive to maximize the amount of scarce resources they devote to instruction: No charter school receives a dime unless conscientious parents actively choose to entrust it with their child’s education.

In contrast, conventional public schools remain the default option, with most students assigned on the basis of ZIP code, not parental choice. If charter schools were diminishing the quality of instruction by misallocating resources, they would lose students and eventually be forced to close.

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