As I walked out to my car, juggling coffee, lunch and books, I sensed something was wrong before I saw it. Flat tire. I briefly considered just trying to air it up and even turned on my air compressor. But I knew better. For some reason that only the universe understands, the passenger side rear tire on my vehicle is prone to accidents, injury, and even death. I blame my wife. She was the first person to smack that particular tire against a curb while making a right turn. The rest of the car is on its second set of tires but the rear one is on tire number four. The rest have died from glass, metal shards, a stray bolt, and the curb at Eighth Street and Cimarron.
Fortunately I had obtained a spare tire from the junk yard (at considerable savings from what the dealer charged.) It was one of the so-called donut spares and was marked quite clearly that speeds in excess of 80 kilometers per hour were dangerous. After changing the tire and cleaning up, I headed to work, dutifully keeping my speed at 80 kph. Now, at this point, some might think I’m some sort of mathematical whiz at being able to convert mph to kph while driving, texting, and drinking coffee. Actually, my car, like all cars, has both scales on the speedometer. All I had to do was watch the small white numbers instead of the large orange ones. This simple trick is at the heart of understanding the problem of why the U.S. is the only country still avoiding the metric system. Our rejection of the metric system costs us trade and therefore jobs. There are a lot of goods we can’t export because of incompatibility with the rest of the world’s measurement system. Americans hate the very idea of the metric system and that has to fall squarely on the back of educators. Schools have been teaching metric since the Sixties and all they have to show for it is 2 liter soda bottles, and even that’s actually compliments of the 7-Up company not teachers.
I understand the difficulty. When I was still in college I tried to tutor my bride in the metric system so she could pass her biology class. I taught her exactly the way the biology professor was trying to teach it: lots of conversion worksheets. I failed miserably except for making Kim miserable as well. Divorce, I almost accomplished. Mathematical understanding not so much. So when I began my teaching career, I made it one of my goals to figure out what the obstacles to learning metric were. What I discovered is that textbooks and teachers make the metric system way harder than it needs to be. First, by teaching every part of it and secondly, by forcing learners to convert back and forth between metric and traditional measurements.
As my speedometer example demonstrates, no one needs to convert one measurement into another in everyday life. Exhibit A is thermometers. You don’t need to multiply the outside temperature in Fahrenheit by the age of your oldest child and then divide by your IQ score in order to find the temperature in Celsius. Just look at the other scale on the thermometer. Over time, you will realize that 68°F to 72°F is the same comfort zone as 22°C to 24°C. No conversion is necessary. Measuring cups have two scales. One doesn’t need to know how many milliliters are in 4 ounces. Just turn the cup around.
The other problem is that teachers teach way more of the metric system than is needed or useful in everyday life. They want to teach hectometers and deciliters and all sorts of useless measurements. It’s like asking people to memorize how many pecks are in a cubit. Who the heck knows or cares? When you travel to a country that uses metric, you quickly discover there are only a couple of units you need to know. In fact, I can teach most people the metric system in five minutes. If a person can calculate how many dimes or pennies are in $3.20, or inversely how many dollars are in 460 pennies, then that person can learn the metric system. Or at least all they need to know to function in daily life.
Don’t believe me? Then let’s try it. To use the metric system in daily life, you only have to memorize six words and a simple rule. The rule I already alluded to. The rule is that when you change from bigger units to smaller units (such as dollar bills to dimes) you multiply by 10, 100, or 1000. In my example, $3.20 gets multiplied by ten since dimes are smaller than dollars and there are ten dimes in a dollar. So our answer is 32 dimes. If we convert to pennies, we multiply by 100 because there are 100 pennies in a dollar and our answer is 320 pennies. Is that too difficult for most people? If it is, we should take away their driver’s license. Or at least their texting while walking privileges.
The inverse of the rule is also easy. When you change from smaller units to bigger units then you divide by 10, 100, or a 1000. Again from my example above, 460 pennies divided by 100 (because there are 100 pennies in a dollar) and we have $4.60. To convert 460 pennies to dimes we would divide by ten (because there are ten pennies in a dime) and we would get 46 dimes. Most people have intuited this rule but never had it pointed out to them. And you don’t even have to do the math in your head (even though it is simple) because most people have cell phones, tablets, and computers that have built in calculators.
Next, one has to know what units are used for what measurements. The metric system uses meters (m) for length, liters (l) for volume, and grams (g) for weight. Liters should be easy since people have been buying soda in 2 liter bottles since the Seventies. I haven’t found anyone who has too hard of a time remembering which units go to which measurements. People have seen enough meter sticks, soda bottles, and grams on the side of packages to have internalized this knowledge.
That leaves memorizing the prefixes that change the base units (liters, meters and grams) into bigger or smaller units of measurement. These prefixes make life easier because the prefixes mean the same thing every time you use them and at least one is already commonly used. Centi means 1/100. Most people already know this one. One cent is 1/100 of a dollar. A centimeter is 1/100 of a meter, a centiliter (cl) is 1/100 of a liter, and a centigram (cg) is 1/100 of a gram. Milli means 1/1000. So a milligram (mg) is 1/1000 of a gram, a milliliter (ml) is 1/1000 of a liter and a millimeter (mm) is 1/1000 of a meter. Kilo means 1000 of something. Therefore a kilogram (kg) is 1000 grams (all drug dealers know this one), a kiloliter (kl) is 1000 liters, and a kilometer (km) is 1000 meters.
That’s all there is to it. And we don’t even use most of these. Daily life and work require: km, cm, mm, l, ml, Kg, g, and mg. The rest are seldom used. Truckers might need kiloliters. But that’s it. I know that people will still be reluctant to change. For example, people worry about how to convert Grandma’s recipe for blueberry brisket with cauliflower compote. But it’s really an unnecessary fear. With Donald (I could shoot somebody in the middle of Times Square) Trump in office, we could get the country to convert overnight. Just like every other country prior to us, there would be national angst until a month after we convert and then nobody will remember what the fuss was.
Of course I could be wrong about all of this. I was, after all, taught the metric system by Canadian nuns. And when they hit us with a meter stick, it left a lasting impression.
