I was in grade school in the 1950’s. It was way back then at least as I can remember that there was a big deal made about using the metric system. It was as if the U.S. (English, S.A.,E, etc.) measuring system of feet and inches (and all the rest) was under attack by the Metric system used in Europe and/or the “rest” of the world. It was the world of science and some engineering that was promoting this new “cause”.
As a “kid” what did I know. But I did get the impression that the USA was not going to change without a fight. It was like a foreign invasion, The emphasis was how to CONVERT from one measurement to the other. Awful conversions factors are required and it really was a math test.
I always thought it was stupid and awkward to do the conversions. I think it just made teachers feel good to have something in a math application they could grade (measure) for accuracy. Hmmm… Are grades in metric or English? How do you convert? Ha!
So we grew up dealing with both systems in grade school and awkwardly converting. It was like we had to preserve our “native” language. In reality, the total metric system actually has a lot going for it, but don’t say that too loudly.
Later in my life many published papers and drawings, where measurement are used, would group both measurements together. Let’s see that’s about 2 inches (51mm). That’s still done today. Most everything in commerce has both systems used in marketing as we are in a world wide economy. A rather clumsy accommodation, not likely to change soon.
Measurements and math are a form of language. In the real world, a person fluent in several languages actually thinks in those languages. I have friends that sometimes pop between two languages without knowing. “Whoa! Chalo, come back to English…” would make him laugh.
After breaking the constraints of low level educators forcing conversion factors on me, I found it far easier to THINK in both systems rather than convert. There is room in the human brain for both systems to run on their own track just like knowing multiple languages. Conversion is unnecessary.
The conversion training has given me a reference of comparison but I no longer convert in order to understand. I think in both systems. I do use conversion in writing for a specific need such as when I use a machine that is calibrated in the other system from my original measurements or drawings.
Even then, EXACT conversion is not necessary except for exact fits or tolerances.
I do have two sets of hand tools but I can look at a bolt head and tell what wrench is needed. That is the practice of experience that is really needed, not converting between the two systems.
So today I readily jump between both worlds like they were one. Neither system is lost. I often design using metric measurements because I have machines that are calibrated for metric. I don’t consider at all what a measurement may be equal to in the English system. I have no need for that.
I never think, “What’s 3 and five eights in metric?” I’ll just make it 90 (or 92) millimeters, because that’s about the size I need. If I am doing woodworking or carpentry I am thinking feet and inches. No conversions at all.
In my machine parts work the measurements are all in decimal both English and Metric. Fractions are not used but sometimes still show up on a drawing and hole sizes. It is the fraction that needs converted to decimal.
For me it all adds to the enjoyment of working with numbers. It’s like knowing the secret code of flowing between all the methods of measurement. A society that has secrets that are not secrets at all. Anyone with enough ability can master both systems.
Practice conversion at first but move on to thinking in the native language of what you are doing and where you are (living). Conversion is for the tourists.
In the USA we have become a bi-lingual measurement culture. It seems to work.
Next hurtle is languages That is a whole different mountain to climb. Or is it?