Responding to this post about the metric system from Doug Noon:
In Canada, the metric system was implemented gradually while I was in school - first distances and temperatures, then weights and measures. The parts that were used, I learned. the parts that were not yet in use, I didn't learn. The result is that my intuitive sense of measurement is a mixture of the two:
- temperatures - I understand Fahrenheit, but if asked, will always respond with a Celsius temperature, and it bugs me when weather maps (eg., from Weather Underground) are all in Fahrenheit, so much so that I only use Environment Canada online weather maps.
- distances - kilometers only. I understand miles, but they're too long. Driving 100 km in an hour is something that makes sense to me. Shorter distances? Meters. There's a large grey area there - I don't have a good intuitive idea 0f 20 feet or 60 yards, whatever. And please don't give me a length in 'football fields'.
- height - feet and inches. I know I'm just a hair under 6 feet. No idea what that is in centimeters. When I'm measuring wood for carpentry, I will use both inches and centimeters - whichever way the ruler is facing, I don't care.
- weight - pounds and tons. I know a kilogram is 2.5 pounds. But I don't know how many kilograms I weigh (I'd have to calculate it). I know what a gram is, but I don't use grams any more. There's 28 grams to an ounce. But I don't really know how heavy an ounce is.
- liquid measures - don't ask me what a fluid ounce is, I have no idea. I understand liters. Quarts are like liters, only a bit bigger. I know gallons, but I never have enough of any fluid to actually have a gallon of anything. Yet, when describing fuel efficiency, I only understand miles per gallon - 8 is bad, 40 is pretty good. I haven't a clue what liters per 100km looks like. What is bad? I don't know. 5?
- land - acres and square miles. But, mostly,. acres. Because we had a 1 acre lot when I was a kid. And the land where I lived was divided into quarters (160 acres), 4 of which made a square mile. That's what I believe, anyways. Hectares? Funny square acres.
- energy - my mother dieted so I understand calories. Only in theory, however. I actually had to look up a couple of weeks ago how many calories people should consume in a day, 2000 - 3000. Which makes 60 calories good, 400 calories bad. Unless you're starving, in which case good and bad are reverse. The equivalent in joules? Please, I don't even know where to begin. That said, I consume power in watts and kilowatts, and pay for it by the kilowatt hours. Every appliance is compared to my gold standard, the 2500 watt hair dryer I bought as a kid. Horsepower? No idea what that is. Cars have, what, 12?
- pressure - I read a lot of science fiction, so I understand 'one atmosphere'. Kilopascals? Forget it. Millibars? Forget it. For pressure, I understand 'low' and 'high'. For my bicycle tires, I use PSI - but I had to look up a few months ago how many PSI to fill my tires (65). How many PSI is the atmosphere? Not a clue.