Some teachers have the expertise but lack teacher training.

Ensuring that California's classrooms are filled with only highly qualified teachers is a noble and worthy goal of the K-12 educational system. However, federal and state regulations have turned the words "highly qualified" into narrowly defined criteria that threaten to exclude many capable and effective teachers.

"No uncredentialed teachers" was a rallying cry under former Gov. Gray Davis' administration, and it is a key part of the federal No Child Left Behind law. The phrase makes a good political sound byte, has union support, and provides a clear managerial mandate. But firing all non-certified teachers is not always in the best interest of schools and students.

To a large extent the push grew out of poor, urban school districts which faced such acute teacher shortages that administrators hired just about anyone with a bachelor's degree to teach any subject, regardless of expertise. It was a legitimate problem that needed to be corrected.

But what about when credential mandates force out knowledgeable and smart professionals simply because they don't have the state certification? That's now happening at many schools as they scramble to meet the requirements of the No Child Left Behind law and various state regulations. The impact is felt most in the higher-level math and sciences, programs that face chronic teacher shortages and often recruit mid-career professionals, master's graduates and Ph.D. candidates.

Nor can one assume that credential schools, which mostly focus on the teaching process, automatically produce good teachers. Some programs are extremely valuable and others are a waste of time.

Fortunately some alternatives to the state-certified credential programs are appearing. California has begun implementing teacher internship programs that will allow potential teachers to prove their competency in a given subject through tests, and prove their teaching abilities under administrative supervision. That's an excellent start.

Still, strict regulations have made many administrators nervous about losing federal funding, and that has led to some good teachers losing their jobs.

Credential programs are not the only worthwhile path to the classroom. The state and federal governments must provide and promote legitimate alternatives.