Helen F. Ladd is a distinguished professor of public policy and economics at Duke University.

In this article, which appeared in the News-Observer in North Carolina, Ladd explains why the schools need experienced teachers, not just a steady supply of novices who serve for two or three years, then leave.

She writes:

In an effort to keep educational costs in check, America’s cash-strapped states, local school districts and charter schools are hiring less-costly novice teachers. Some of the new hires are energetic college graduates supplied for two-year stints by programs such as Teach for America.

In the late 1980s, most of the nation’s teachers had considerable experience – only 17 percent had taught for five or fewer years. By 2008, however, about 28 percent had less than five years of experience. The proportions of novices in the classroom are particularly high in schools in underprivileged areas. Some observers applaud…