I sat in on the "remedial math" classes at the local community college.
A fair amount of time was spent on reading a ruler - some of the quiz questions were:
Which is longer = 5/8 or 3/4? How long is the distance between the 1-1/4 and 2-7/8 marks on a ruler?
I was surprised at how many people did not seem to know how much "a yard" was when they were at a cutting table.
For those that know both the metric system and system mostly used in the USA - which is easier for sewing?