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This is not a fully thought out response, more stream of un-consciousness:
1) Are you saying you would call it US customary units instead of US customary system? I could certainly support that because it is not a system. I think the debate needs to start with a nicer term than "hodge-podge of traditional artifacts." It is, it just doesn't get the debate off to a good start. Note in your table that you are missing a number of decimal points and leading zeroes, the first being 0.125 MI. If you wish to be complete, you are also missing the fathom (6 feet), the (surveyor's) chain (66 ft), the naval chain (720 ft) and the league (3 mi) as well as the nautical mile (1852 m). However, most of those as well as the rod and furlong are little used, so only the inch, foot and mile have much practical usage.
The biggest problem with customary units is the hodge-podge of inter-relationships as shown in your table and which get worse as you expand to other quantities. Areas and volumes are certainly measured in square and cubic inches and feet, but also in specialized units. The acre is 43560 ft². The gallon is 231 in³, but if you have to convert a cubic foot (1728 in³) to gallons, that is 1728/231 = 7.480519 gallons. The bushel, the basic of dry volumes, is 2150.42 in³ and does not have an integer relationship to the liquid gallon. The current American definitions of gallon and bushel are those passed by British Parliament around 1700. They are the very measure of the ruler against whom we rebelled in 1776. (We did not avail ourselves in the 1824 improvements of the Imperial system used in the UK).
2. SI quantities are generally inter-related by powers of ten. The decimeter is 0.1 m. The liter is defined as 1 cubic decimeter (1 dm³). It is easy to determine 1 m³ = 1000 L. How many gallons in a cubic yard? The hectare (used to measure agricultural plots) is 10000 m² (about 2.5 acres). It is easy to see a square 100 m x 100 m is 1 hectare. What is one side (in yards, please) of a 1 acre square piece of land.
It won't matter until high school, but the customary units become more confusing when you begin teaching mechanics (parts of a physics course). Newton lied and f is not equal to ma, if you use Customary units. The pound is used for both mass and force and has to be distinguished by lbm and lbf to distinguish the two. Still f is not ma unless you develop supplemental units (either the slug as a modified unit of mass, the poundal as a modified unit of force, or measure acceleration in units of g's. In the SI, f = ma, and 1 newton is the force required to accelerate 1 kg at 1 meter per second squared. A one pound force accelerates a one pound mass at 32.174 ft/s² or 1 slug at 1 ft/s², but a slug is 32.174 lbm. It is a nightmare to work science or engineering problems in customary units (although I admit NASA LOVES doing it).
3. I'm not the right person and will let others speak to this.
4. The US Army maps entirely in metric, using the Military Grid Reference System since before the Vietnam era. The basis of it is the use of 100 km squares, and coordinates in meters within the square. (The Navy and Air Force tend to be less metric)
I think you need at least one more category and that is Industry. Quite a bit of US industry is metric and wants workers who understand metric. Workers who don't are useless. The domestic auto industry is entirely metric and electronics and phamaceutical industries are totally or mostly metric, as are MANY business which export a lot. You might look at the USMA archive:
and message #51520 for a recent example. Students who do not have a good understanding of metric will simply miss out on many job opportunities, and could be said to be "not educated."
You may wish to point out that there are no primary physical standards for any US customary units. They are simply declared fractions of metric standards that we received as one of the signers of the 1875 Treaty of the Meter. This has been the case since 1893 (Mendenhall Order).
Finally, as a resource to you, I would suggest you download NIST SP 330 and SP 811 as metric resources (they will be too detailed for elementary or middle school instruction, but the ultimate resource). You may also want to meet with someone in the metric programs office of NIST (part of Dept. of Commerce) to see how they could help. --- On Fri, 3/16/12, Metric Rules Info <[email protected]> wrote:
From: Metric Rules Info <[email protected]>
Subject: [USMA:51526] Feedback please- Metric Rules
To: "U.S. Metric Association" <[email protected]>
Date: Friday, March 16, 2012, 11:44 AM
I am the Executive Director of a new nonprofit created to drive Science, Technology, Engineering, and Mathematics (STEM) curricula towards greater focus and coherence; we believe that no single change would impact this objective more successfully than metric-only STEM instruction. I am getting some state- level traction and I have been asked to submit a paper stating my case. The GREAT news is that interest has come relatively fast (6 months) but the flip side is that I have not been able to fully flush out my thoughts and gather facts/ feedback on some key points. I am hoping that this very knowledgeable group will help me craft the most effective, but accurate, messages.
Any and all comments (positive or negative) are greatly appreciated.
- US customary units- I have stopped calling it the US customary system. The word system used to describe customary units is a misleading term; it’s not a true system. It is more correctly described “as a hodge-podge of traditional artifacts and international legacies clustered and upheld through our continued teaching of them.” I intentionally used the word “teaching” instead of “usage” because the reason customary units are still part of consumption is because that’s what most American’s were taught in school and we are focused on education. I then attempt to demonstrate this point with the below table. Questions- What do you think of my new “catch-phrase” to describe our collection of customary units and the visual representation of it? I agree, there must be a better way to visually illustrate it but I can figure it out?
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US customary (length) |
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1 mile= 8 furlongs=320 rods=1760yd= 5280ft= 63,360in |
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1 furlong= 125MI= 40 rods= 220yd= 660ft= 7920in |
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1 rod= .003125MI = 0.025 furlong = 5.5yd= 16.5ft = 198in |
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Yard (standard)= 000568181818MI= 00454545455 furlong= 0.181818182 rods, =3ft, =36in |
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1 foot= 0.000189393939MI, =.00151515152 furlong, =.0606060606 rod, 1/3yd, =12in |
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1 inch= 1.57828283 × 10-5 miles=.000126262626 furlong, =.00505050505 rod, =.0277777778yd, .0833333333ft |
- SI units- I am trying to convey the true system of SI units. I state that not only are the SI units connected but that the SI measures themselves have defined relationships. I am particularly interested to know if a spatial measurement (length, area, & volume) correlation/ relationship exists? If so, how would you explain it to a 6 year old. And how would you explain the relationship between meter and liter to a 6 year old? My background is not in Science; I am learning as I go and would greatly appreciate any interesting connection points between SI measures. I have noticed lots of research around the question of why US students have so much trouble understanding spatial measurement. Is one factor the use of our customary units? Would metric-only instruction significantly improve a student’s understanding of spatial measurement? If so, how?
- Healthcare- Any numbers about accidental injuries/ deaths related to conversion errors. This feeds into the issue of educating a workforce to “think” and live in an inch-pound world but financially rewarding occupations that function in a Metric one. (Side note, I became interested in the inch-pound/ metric debate after my then infant son was prescribed a double dose of medication, from what we assume was a weight conversion error. Unfortunately, he was born with some medical issues but he is now a healthy, funny little man)
- Military- Any numbers about accidental injuries/ deaths (or even miscommunications) related to, again, educating people to “think” in inch-pound world then asking them to function in a (stressful) metric environment. Also, I would like to think about an approach (or defense) to any possible “this is anti-American conversations” by pointing out that the military uses metric units extensively. How could I make this point delicately but clearly? Any thoughts?
Like you, I personally believe full metrication is the best approach. That said, Metric Rules is only focused on addressing deficiencies in STEM instruction. By not directly promoting consumption and production changes, I hope to keep the conversation centered on the best path towards creating a STEM-literate workforce. I wish to stay out of the quagmire of politics. I truly appreciate your consideration and time answering these questions. I am new to this movement but this I know, it will take our entire team for us to be successful! The complexity and general disinterest is simply too great. Metric-only STEM instruction would only be a base hit (although I think it’s a double) compared to the homerun of full conversion. But, at this point, I am just happy to be in the game….
Cordially,
Bridget Nagarajan
Metric Rules
Metric Only STEM Education in the USA
    
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