Older teachers are beginning to retire in large numbers, just as student enrollments are beginning a decade-long rise. The two factors spell shortage.

• As of the 1993-94 school year, one-quarter of all public school teachers were 50 or over.

• Almost one-third of all U.S. teachers have been in the profession for over 20 years -- and more than six of every 100 teachers are leaving the profession each year.

• Most are retiring, but one in every five is simply deciding to quit.

• The teacher corps is expected to total 2.7 million in September 1997 and three million by 2006.

Increasing retirement by older teachers will mean that school districts will have more to spend, since public school teachers move to the top of pay scales after anywhere from 12 to 20 years. As a result, half the teachers in many districts now earn the maximum salary.

Meanwhile, public school enrollment is expected to hit 46.5 million in fall 1997 -- with two million more added by 2006.

With the growing demand for teachers certain to be strong, there is the fear that standards will fall.

• Even now, about 15 percent of high school math teachers not only don't have a major or minor in mathematics, they aren't even certified to teach it.

• Many school districts now offer emergency teaching credentials that allow would-be teachers into the classroom before they earn their teaching credentials -- or even before they finish college.

Source: June Kronholz, "Teacher Retirements Portend Acute Shortage," Wall Street Journal, July 24, 1997.