“If you have more students, you need more teachers,” Duncan superintendent Sherry Labyer sensibly told the Duncan Banner in February. If, for example, 250 new students show up to enroll in Duncan’s public schools, then obviously administrators will need to hire more teachers.

Of course, the corollary is obvious. Simply take Mrs. Labyer’s statement and substitute the word “fewer” for the word “more.” If, for example, 250 fewer students show up to enroll in Duncan’s public schools, then administrators would not need to hire as many teachers. In other words, those instructional costs aren’t fixed. They’re variable. Indeed, economist Benjamin Scafidi estimated in 2012 that only one-third of Oklahoma’s education costs are fixed costs, whereas two-thirds are variable costs (costs that change with student enrollment).

In a recent argument against parental-choice legislation, Steven Crawford, executive director of Cooperative Council for Oklahoma School Administration, told the Tulsa World that “costs don't go down just because a kid leaves. You don’t get rid of a teacher every time a kid leaves, or you don’t close a building.”

True enough, certain costs are fixed. No reasonable person would claim that a school administrator should “get rid of a teacher every time a kid leaves.” But if 25 kids leave, or 250 kids leave, that’s a different story. Some costs are variable. Unless, of course, Mr. Crawford is prepared to say that he doesn’t want increased funding if 250 new students show up.

For some additional clear thinking on fixed costs, and to see why school choice is good news for Oklahoma’s state budget and for local school district budgets, I urge you to read Dr. Scafidi’s latest article here.