Drip, Drip, Drip: Hiring enough teachers to fill America's classrooms is like pouring water into a leaky bucket.

• Author: Weiss, Suzanne
• Position: EDUCATION

For many years, it was widely assumed that two converging trends--the aging of the nation's teacher workforce and rising K-12 enrollments--would inevitably lead to severe, widespread and sustained teacher shortages.

But that assumption was called into question by the National Commission on Teaching and America's Future back in 1996. The problem wasn't the overall supply of teachers, said the authors of "What Matters Most: Teaching for America's Future." There was, and would continue to be, a more than adequate number to meet demand. Rather, they said, it was the mismatch between supply and demand in certain subjects and certain school districts that left positions unfilled. And that mismatch was attributable mostly to the large number of teachers leaving their jobs for reasons other than retirement.

Policymakers needed to change the question, the report said, from "How do we find and prepare more teachers?" to "How do we get the good teachers we have recruited, trained and hired to stay in their jobs?"

Today, the commission's report is recognized as having had a profound and lasting impact on the landscape of public education, spawning an array of policy changes, reforms and innovations focused on teaching quality. It also spurred wider, deeper research into teacher supply and demand.

Tackling Teacher Turnover

Among the most influential analyses has been a series of reports, beginning in the early 2000s, by Richard M. Ingersoll of the University of Pennsylvania's Graduate School of Education.

Recruiting new teachers--the dominant policy strategy in many states--isn't enough, Ingersoll said.

"Current policies not only will not solve school staffing problems, but they also divert attention from the primary underlying problem--the manner in which schools are managed and teachers are treated," Ingersoll said in his 2001 report "Teacher Turnover, Teacher Shortages and the Organization of Schools."

School staffing problems are neither synonymous with nor primarily due to an insufficient supply of teachers, Ingersoll said. Rather, they result from "excess demand" created by large numbers of teachers leaving their jobs.

Ingersoll described teacher turnover as a multidimensional--and widely misunderstood--phenomenon that takes a variety of forms: transferring within a district, taking jobs in other districts or states or leaving the profession altogether. Contributing to high turnover are low salaries, student discipline problems, inadequate support...