Don't get me started Bill! As a school teacher I was required to educate pupils from Y1 to 6th form to be able to use feet, inches, miles, oz, lbs, pints, gallons (but not quarts) etc AND mm, cm, km, ml, L et al... still teaching this even though we went decimal 55 years ago! Honestly it used to do my head in!
I should add that I was still doing this up to 7 years ago when I retired aged 55.21 years.