MeepoTheMighty said:
The problem that we have in this country with not understanding the metric system is that basically, nobody has any fundamental grasp of metric measurements. Everyone knows about how long an inch is, but they have to think about how long a centimeter is. I don't really understand how every other country managed to just switch all of a sudden without everyone being confused.
I grew up in Australia with the metric system, but now live in the US, and I have the exact reverse problem. Over the years I've learnt how to roughly convert to the units I understand. For example, I now know that a pound is about half a kilo; a quart is a little less than a litre, and so a gallon is roughly 4 litres and a cup about 250 ml; a yard is roughly a metre; a mile is about 1 and half km, but for practical purposes it usually works to think of it as a "big kilometre." All of this is good enough for things like cooking and checking that the answers of calculus problems I work for my students are in the right ballpark.
I still have problems with the internal conversions of the US system, though. For example, I can never remember if a pound 16 or 12 ounces, or how many feet to a mile (it's 5000-something, I think).
My parents, who have used both systems for significant parts of their lives, don't seem to have any trouble working in either system.
As for how you accomplish the change, you basically have to have a government with the will to make it stick given the inevitable complaints; plus good public education and some related laws to back it up. And then keep it up for a generation or so. I know that in Australia it was illegal to advertise quantities using the old Imperial system until very recently. You couldn't sell your fruit by the pound, only by the kilo. A law like that would probably be against the free speech parts of the US constitution, and many Americans would resist it on principle even if it was constitutional. But on the flip side, there was a lot of education in the 60's in Australia about how to convert to metric in practice for people like merchants and construction workers.
I've never understood complaints like those of trancejermey's (in fact, I'm not even sure if he's serious or trolling). I've heard people say that it's stupid that, for example, their quart of milk becomes 0.94 litres (or whatever it is exactly), when in practice what happens is that your quart of milk becomes 1 litre (and you get an extra 5% or so volume). In fact, as far as I can tell, A 1 quart carton and a 1 litre carton are identical. Your 2-by-4 piece of wood doesn't become a 5.08-by-10.16, it becomes a 5-by-10. Similarly, the TV news doesn't usually give temperatures with decimal places. It's good enough to know that the temperature outside is 37C or 38C to know that it's bloody hot, you don't say that it's going to be 37.7C tomorrow any more than the US weatherperson says it'll be 100.2F outside.
