The July 15 news story "Effectiveness of Teacher Certification Questioned" notes that a "new" study -- using seven-year-old data -- finds that students of teachers with emergency teaching certificates perform about as well in math and science as do students whose teachers hold "regular teaching credentials." But The Post fails to tell readers that the study makes highly suspect comparisons.

As just one example, the study compares 74 teachers without certification, 60 with emergency certification, 43 with probationary certification and 2,930 with standard certification. Beyond the problems that exist with such ridiculously disproportionate sample sizes, the study plays fast and loose with terminology. Most states do not issue something called "emergency" certification. They use various terms such as "temporary," "provisional," or "probationary" -- and those different terms can, in different states, indicate varying levels of preparation for teaching. So who exactly are these teachers with "emergency" certification? One can't really tell from this study, so one can't really do a fair comparison.

The world has changed in seven years, as states have acted to reduce class size and cope with growing enrollments -- and to raise standards for students. That different world is not reflected in this study. California alone has thousands of uncertified teachers in classrooms. Now is not the time to lower standards for teacher preparation, as the article implies. Certification procedures don't guarantee excellence, but they do filter out those who are clearly unprepared for the classroom. Our children deserve at least such a minimal guarantee against incompetence.

NAT LaCOUR

Executive Vice President

American Federation of Teachers

Washington