Nancy Evans, age 14, of Philadelphia, Pa., for her question:

WHY MUST WE LEARN THE METRIC SYSTEM?

Pen pals often send Andy jokes and other polite complaints about the so called new math. Now we are told that students must strive to learn the metric system. Well, Andy never found a good reason for wrestling with the new math. But there are some mighty good reasons why we should buckle down and learn the metric system.

Nobody likes to tag along at the end of a parade. But if we fail to meet the challenge of the metric system, that is just what will happen to us and to our country. One by one, all the other major countries have changed to the neat metric system. Only the United States stubbornly refuses to give up its clumsy weights and measures.

Not that Americans have neglected to consider the problem. Actually the great debate has been raging on and off through the past 150 years. Thomas Jefferson proposed to the first Congress that young America should give up the old system inherited from England in favor of the new metric system. The arguments against it were different but just as stubborn as they are today. Some said the metric system would be a sellout to a foreign power. Others claimed it was against God's way of counting. So for a long time the English speaking countries clung to their clumsy old inches, feet and miles.

Then one by one our former allies listened to the sound reasons for switching to the metric system. The whole thing is based on 10s. This is much easier and quicker than coping with, for example, inches and ounces in 12s and 16s. Even computers find it easier. It also simplifies measuring jobs and saves a lot of time.

But the most urgent reason we should change is the fact that the other major countries already have done so. They use the neat metric system to build their tools and machines ¬and naturally it is simpler to trade with other countries who do the same. If we wish business abroad, it is high time we joined the parade.

A halfway bright student can learn the whole metric system in a few hours. The problem is converting our old yards, pounds and quarts into meters, kilos and liters. However, other recent converts report that this is no big headache. Everyone carries around simple charts that translate the old weights and measures into the new  and the whole thing is mastered in just a few weeks. True, the changeover is tougher for manufacturers who must change basic tools and equipment  but much of this work already has been done.