OK, some guys from Columbia, Missouri are designing a 3000 m² garden for an Expo in Korea. http://www.columbiamissourian.com/stories/2011/05/31/columbia-garden-be-exhibited-south-korea/
The lead guy says about metrication: For Lowery, the biggest challenge was having to use the metric system. "I set up the drawings so the other members could work in feet, and then I would make the conversions," Lowery said. "I was the converting guy." I assume the boundaries, paths, etc are all specified in metric. I know Pat will hate this, but I would have given everyone a dual tape measure (to help them envision plant spacings) and told everybody I expect their piece in rounded metric. Plants are quite non-fussy about exact spacing. Plants that should be 12" apart (by American standards) are just as happy 0.3 m apart (or 300 mm if preferred). No way would I be the "converting guy" for a bunch of guys who get an all expense paid trip to Korea. Learn metric or stay home! (As a manager, I understand motivating the troops. :) ) I would not have taught them any conversion; they can convert well enough on their dual tape. I know Pat will disagree, but a dual tape is a good way to identify a round metric number around an inch dimension you have in mind. It is not a bad crutch for a a couple of jobs, but it should then be replaced with a metric-only tape. It can be used to get across the point of sensible rounding very well. I'm a bit surprised they left the 3000 m² area in the story, but then the drawing only has a 50 ft bar on it for scale, no metric reference at all.
