Generals don’t have to start as privates. CEOs don’t start in the mailroom anymore. For that matter, Horace Mann himself never had any classroom teaching experience. Yet a new story from New Haven raises this question again: Why is it a bad idea to put people in charge of schools if they’ve never been teachers? This morning I’ll offer my three reasons. Are they enough? Or do teachers just feel an irrational desire to be flattered into thinking that their classroom experience matters?

He’s betting $100 million that I’m wrong…

Here’s the background: Mega-rich ed donor Eli Broad just dished out a cool $100 million to Yale. Broad (apparently pronounced “Brode”) moved his center from LA to Yale’s business school. The goal is to offer an academic center that will offer, in the words of Yale’s leadership,

a tuition-free master’s degree program for emerging education leaders, advanced leadership training for top school system executives, and an extensive research endeavor aimed at assembling the premier collection of data on public education leadership.

Just in case you missed it, this program in school leadership is not part of Yale’s teacher-training program. In fact, Yale no longer offers teaching certification. No, this program will be part of Yale’s business school. The school leaders emerging from the Broad program will plan to take over districts and operate them more efficiently and productively, more like businesses.

Will it work? As Curmudgucrat Peter Greene pointed out in the pages of Forbes Magazine, Broad’s track record in education is not great. As Greene recounts,

Many of the most familiar names [of former Broad program grads] are familiar precisely because of their level of failure. Robert Bobb had a lackluster showing in Detroit. Jean-Claude Brizard received a 95% no-confidence vote from Rochester teachers, then went on to a disastrous term of office in Chicago. Oakland, CA, has seen a string of Broad superintendents, all with a short and unhappy tenure. Christopher Cerf created a steady drumbeat of controversy in New Jersey. Chris Barbic was put in charge of Tennessee’s Achievement School District, and resigned with all of his goals unfulfilled (and recommended another Broad grad as his replacement). John Deasy’s time at LA schools ended with a hugely expensive technology failure.

Yet in spite of this record, Yale seems eager to take the money and open a program for similar leaders. To be fair, Yale’s not alone. There seems to be no general objection to elevating school leaders who have no classroom-teaching experience. It’s not only Queen Betsy. Obama’s Ed Secretary Arne Duncan also had no real teaching experience.

So why do so many experienced teachers think that leaders should have a teaching background? Why do so many clamor for our next President to install a teacher in the top ed job?

Easy. It’s not that learning general business and management skills can’t be helpful to running a school district. But having classroom teaching experience gives people three big, necessary advantages when it comes to building- or district-level school management.

First, having teaching experience cures us of the misunderstandings that we all have from our time as students. Unlike most jobs, almost everyone thinks they understand school, because we all spend a lot of time in school as students. In order to be an effective school leader, however, we have to go through a difficult process of giving up our tendency to assume that our experiences are somehow typical or representative. In every case, they are not.

One of the first lessons of a lot of new teachers—the talented group of people I get to work with—is that most of their students are not like them. A lot of new teachers remember school fondly. They often excelled in their classes and enjoyed their time in class. That’s a big part of their reason for wanting to become teachers in the first place. It is only when they start teaching that they realize how unrepresentative their own experiences are. Working with groups of students teaches teachers that there is no single one-size-fits-all approach to learning and growth.

And that brings us to the second necessary lesson that teachers learn. Unlike business leaders, teachers do not plan to ignore parts of their “market” that are not “productive.” Unlike business leaders, teachers do not expect that some of their “customers” will not buy in. Unlike business leaders, teachers learn to help every single student that they work with; they don’t concentrate on the “likely buyers.”

Third, and maybe most important, teachers learn things about real schools that even smart, informed civilians never seem to understand. Let me give you one example that helped me understand this lesson. I get to teach different classes. I teach an undergraduate course that introduces juniors and seniors to basic issues in American education, such as charter schools, unions, and the role of religion, race, gender, and economics. I also work with people who are completing their student-teaching experiences. Both groups of students are intelligent and informed. In fact, they are very similar groups of students. The biggest distinguishing factor is that the student teachers have taught for a few weeks, while most of the undergrads have not yet.

Though these two groups of students are very similar, they have very different reactions to certain issues. In general, the undergrads are enamored of ideas such as using value-added measures to gauge teacher effectiveness. To them, it makes sense: If you want to know how good a teacher is, test their students at the beginning and end of the year. The difference = what the kids learned that year.

Sounds good to smart, informed people. Yet ALL of the student teachers react with horror to the idea. Why? Because after even just little bit of experience as a classroom teacher, students learn that their students are living complicated lives. There is no simple way to slap a number on the changes that students will go through in one academic year. To assume that their teachers are the ones who are driving those changes—to teachers with even a little bit of experience—seems obviously kooky.

For all three of these reasons, it seems obvious to teacher-philes like me that school leaders should have experience as teachers, classroom aides, or paraprofessionals. They might learn important stuff at the Broad Center, but they will miss out on things they can only learn by working with students.