By Sarah Fine -- Why I Left Teaching Behind

"Why teach?" they ask.

Do my lawyer and consultant friends find themselves having to explain why they chose their professions? I doubt it. Everyone seems to know why they do what they do. When people ask me about teaching, however, what they really seem to mean is that it's unfathomable that anyone with real talent would want to stay in the classroom for long. Teaching is an admirable and, well, necessary profession, they say, but it's not for the ambitious. "It's just so nice," was the most recent version I heard, from a businesswoman sitting next to me on a plane.

I used to think I was being oversensitive. Not so. One of my former colleagues, now a program director for Teach for America, has to defend her goal of becoming a principal: "When I tell people I want to do it, they're like, 'Really? You really still want to do that?' " Another friend describes her struggle to make peace with the fact that a portion of the American public sees teaching as a second-rate profession. "I want to be able to do big things and be recognized for them," she says. "In the world we live in, teaching doesn't cut it."

I often feel the same way. Teaching is a grueling job, and without the kind of social recognition that accompanies professions such as medicine and law, it is even harder for ambitious young people like me to stick with it.

In their book "Millennials Rising: the Next Great Generation," sociologists Neil Howe and William Strauss characterize the members of my generation as "engaged," "upbeat" and "achievement-oriented." This is why we become teachers. We seek to challenge ourselves, and we excel at pursuing our goals. Howe and Strauss go so far as to call us a "hero generation." Our engagement also explains why we are leaving the classroom. We are not used to feeling consistently defeated and systemically undervalued.

President Obama also casts himself as a believer in people my age. "They have become a generation of activists possessed with that most American of ideas -- that people who love their country can change it," he proclaimed in April.

The president is right: My generation does seem to care a lot about Important Stuff. We put our lives on hold to canvass for the causes we believe in. We volunteer like our hair is on fire. When it comes to teaching, however, this fire only burns for so long. We millennials are jostling each other for a place at the whiteboard, but few of us stay long enough to see our students make it through. True, many short-term teachers go on to work in education policy -- and they may well be the ones working on big-picture changes to ensure that more people are willing to stay in the classroom.

But high teacher turnover, in my millennial opinion, still matters, even with eager rookies waiting in the wings.

Having a base of teachers who teach for more than a token few years is critical to school reform. It helps principals and school leaders develop trusting relationships with teachers. It helps teachers collaborate with one another. Most of all, it helps students. A teacher with experience is not always a good teacher, but a good teacher is always better after a few years of experience. As my former principal not-so-subtly put it: "The kids don't need one-year wonders. There is no such thing as a one-year wonder."

Four-year wonders are better than nothing, but still not enough.

Sarah Fine was a teacher, department chair and instructional coach at a Cesar Chavez Public Charter School for Public Policy in Washington from 2005 to 2009.