Note on Teaching the Metric System G. WAKEHAM
University of Colorado, Boulder, Colorado OREIGN languages used to be taught by the "vocabulary-translation" system. Lists of native words were matched with their alleged foreign equivalents, and translations "both ways" were used to grind in the new tongue. Untranslatable idioms and more subtle semantic fallacies were sidestepped or ignored. Students rarely learned to think in the strange medium. I t was the writer's good luck, as a young child, to attend for a short time one of the very few pre-Dewey progressive schools. We heard the heavy footsteps of the approaching professor, rhythmed to the deep hum of a melodious Brumbass. Six feet tall and heavily whiskered, he was appallingly overpowering. Picking up the nearest convenient object, he bellowed, "BUCH! Das ist ein BUCH!" Then, after a short but impressive pause, "Was ist das?" Shivering in our shoes, and to avert imminent catastrophe, we piped up, "Buch!" Plucking a rose from his lapel, he sang, beautifully, one line of "Roslein, Rijslein, Roslein rot," and bellowed, "SING!" We sang. Holding the book and the rose together, he announced, "Buch rot. Rose rot!" We got it. And we never forgot our German. Modem progressive language teachers use similar, if somewhat less violent, techniques. Science teachers and texts, however, still cling to the ancient vocabulary-translation method. Students learn the names of the metric units and then memorize their approximately equivalents in the barbarious measures of common usage. These figures are distressingly complex and irregular, the actual ratios, of course, being incommensurable, unless one arbitrarily deiines one system in terms of the other. Students work numerous "translation" problems and always, in their own minds, laboriously convert metric-system data into the familiar units. They rarely learn to think in grams, centimeters, and degrees Centigrade. The modem, progressive method, of course, is to junk the medieval, "English" system a t the outset, and start with a metrical tabula rasa. Urge the students to forget feet and inches, pounds and ounces, pints and Fahrenheits, and enter the new field of science-measurementswith clean consciences. Then show them a meter-stick, and explain that it is about one
ten-millionth of the distance between the equator and the north pole. Do not obfuscate the class a t the outset by stating that this ratio is not exact: an "exact" determination of the ratio is, in any case, impossible. Stick to the main point of the demonstration, ignoring all confusing, minor considerations. I t is an unfortunate accident that the meter looks like a yard. If you can get by with it, ignore the yard. If some persistent reactionary points out the similarity, put him in his place by reminding him that he has not followed the original instructions to forget the yard, along with all of its relatives. Do not say whether the meter is more or less than a yard: the less said about the yard, the better. The meter is the thing you are talking about. When the meter has been sufficiently emphasized, have the students estimate familiar magnitudes-the dimensions of the room, the length of the corridor, the height of the teacher, etc.-in meters. Do not bring in rods or miles or any of the discarded heathenisms. With the meter once fixed, it is easy to go on to the other units. The dimensions, volumes, etc., of various pieces of apparatus should be learned from demonstrations. I t is unnecessary-in fact inadvisable-to learn the whole metric system with its rarely used decimeters, dekameters, hektometers, and what-not. Three units each of length, volume, and weight suffice for all common purposes: meter, centimeter,. millimeter; liter, milliliter, cubic millimeter; kilogram, gram, milligram. Probably the most effective method of enticing the students to think in the new medium is to require them to guess the magnitudes involved in various common objects, such as a brick, an egg, a pencil, a teaspoon, a cup, their own dimensions, etc. Some, of course, will betray their lack of imagination by offering hilarious "guesstimates" of their own sizes-anything from an ant to a silo. But even these blunders can he used to stimulate imagination, and the skillful teacher may even perpetrate a howler of his own to cover the confusion of a sensitive student. Only after they have learned to move about easily and freely in the new medium should students be given "translation" problems which rarely have any practical necessity.
