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How to learn the metric system People often say that the metric system is difficult or hard to learn, and many people associate it with math problems. However, the metric system is not hard to learn—most people just try to learn it the hard way. The best and easiest way to learn the metric system is to forget about the colloquial units. Obviously, this is not always possible in the United States, but it is much more difficult to convert between the systems than it is to simply learn some new reference points in metric. For example, if I weigh myself I find that I am 59 kg. Now I know how much that is. I may not be able to say how many pounds that is, but things are a lot less confusing if I just don't worry about it. It is 22 degrees Celsius in this room. By thinking of the number and how the air feels on my skin, I now know what 22 degrees feels like—I don't care what it is in Fahrenheit. This means you don't need to be a math whiz to successfully use the metric system. Do you have to do complex math problems when you buy a gallon of milk or step on a scale that shows pounds? Of course not. Then why would you need to know lots of math to buy a two-liter bottle of Sprite or step on a kilogram scale? And for situations where you do need to use math, using metric units in math is inherently easier than using colloquial units (for example, see the section on area measurements). While the metric system requires less math than using colloquial units, it is ideal for teaching science and math because you can do so much with it: unit conversions, area, volume, rates (speed, flow, current, etc.), dimensional analysis, etc. The main impediments to metrication are an emotional attachment to the old units of measure and apathy. It can sometimes cost money to convert to metric, but that is not the main reason people don't convert. Reference points Learning metric really only requires a few reference points and a way to use them in everyday life. To help me use metric units, I have a Celsius thermometer, a kilogram scale, a liter water bottle, several meter sticks, and a metric odometer and speedometer on my bike. The first three are available at Walmart, the meter sticks are available online from Office Depot, and you can get a bike computer at any bike shop. (If you are ever in Fairfax, VA, I'll give you a meter stick.) When you get a thermometer or scale, get a digital one because these will let you to show only the metric units. It is much easier to think in the new units if you don't have the old ones around. There are times where it can be helpful to get out a calculator and do some math when learning metric. Below this paragraph, there are some links to a worksheet that you can use (if you like) to help you compile a cheat-sheet of metric reference points. These are one-time conversions—once you know the metric value, you can forget the other one. In the rest of this page, I give some examples of reference points. Worksheet: Word format PDF format Topics found below: To understand Celsius temperatures just remember: That is really all you need to know most of the time, except perhaps the boiling point of water (100 °C) and body temperature (37 °C). To understand body weight in kilograms, it is best to get a scale (or change the setting on yours if you can). These can be some reference points:
If you get a scale, you can weigh yourself with and without a backpack full of books or other items to find out how much the backpack weighs. This can give you an idea of how heavy 5 kg or 7 kg is, for example. To understand a person's height in centimeters, it is best to tape a meter stick to the wall so you and others can measure the height directly. These can be some reference points:
One very simple thing you can do to begin using millimeters is to change your word processor (and other software on your computer) to use millimeters instead of inches. After a few weeks of using 20 mm margins or 25 mm margins, it feels completely natural and more intuitive than inches. To change the settings in:
I recently got a kitchen food scale that shows weights up to 2 kg. Now I can know that I ate 100 g of pasta (before cooking) last night! One thing you can do right now to help you understand grams is to look at the package for a loaf of bread. The serving size will probably be one slice, with a weight in grams given. If you get out a slice and see how heavy it feels, you have a reference point right there in your kitchen. When you go to the grocery store, instead of looking at the ounces or fluid ounces on the label, pay attention to the milliliters (mL), liters (L), grams (g), and kilograms (kg). If you have a water bottle that is either 500 mL or 1 L, you can just look at the size of the bottle an get an idea of how much those quantities are. The two liter soft-drink bottle can also serve as a reference point. If you have a box of cereal that weighs 425 g, you just see how heavy the box feels to get an idea of how much 425 g is. Compare the elevation of your town to these values.
Most of these measurements are just FYI—I wouldn't expect the average citizen to know many of these. An exception would be the Earth-Sun distance or the Earth's circumference (notice the round value).
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