Just as California's K-12 population is beginning to nudge up, the state is poised to lose a wave of teachers to baby-boomer retirements, layoffs and burnout. Meanwhile, the number of people seeking teaching credentials to fill those spots is dropping dramatically.

"This is the steepest decline we've seen," said Margaret Gaston, president of the Santa Cruz-based Center for the Future of Teaching and Learning, which detailed the teacher numbers in a study released last week.

It all feeds concern that California - whose school-age population is predicted to grow 4 percent in eight years - will soon lack an adequate pool of qualified teachers, particularly those who can teach science, math and elementary school.

Although some of the teaching-force decrease is the result of declining enrollment in schools, Gaston said, "The