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# Why does the US Have a Different Measurement System?

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• Written By: wiseGEEK Writer
• Edited By: O. Wallace
• Last Modified Date: 21 May 2018
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The US measurement system is a confusing matter and still holds itself apart from the metric system employed by most other countries. There are a few exceptions. Medical and scientific fields use the metric system, and many items for trade are now measured in the International System of Units (SI), also called the metric system.

The US measurement system is based on the English system, or imperial units, though England has now long since converted to SI. However, the change to SI was not an easy passage in the mid 19th century. Though Britain is officially on the metric system, imperial units are still widely used.

Legally, according to laws passed in 1988, SI became the standard measurement system for trade and commerce in the US. SI is also taught in schools at a relatively young age, but it is difficult to make the conversions.

If one initially learns the metric system, it is far easier. Everything is constructed on a base ten approach, so conversion from centimeters to meters is a simple matter. Conversely, the US measurement system is often problematic. It is not consistent in its measurements so conversion is quite challenging.

For example, twelve inches equal a foot, but eight (liquid) ounces equal a cup. Sixteen (weight) ounces equal a pound, but three feet equal a yard. Children must memorize quite a bit to perform appropriate conversions.

Since children usually first learn to measure by inches, the metric system cannot be properly taught until multiplication skills are mastered. An inch converts to 2.54 centimeters, thus anything above ten inches involves two-digit multiplication. This is a skill not mastered by most students until the later part of third or even fourth grade.

If, conversely, the metric measurement system were adopted immediately, children would probably learn it just as quickly as they learn the US system. However, since real-life examples are often included in teaching, this would be difficult to do. If one buys a TV, he or she buys a 20-inch screen, not a 50.8-cm screen. If one purchases milk, the choice is a quart, a pint or a gallon, not a measurement in liters (L) or milliliters (mL).

In general, consumer products still adhere to the US measurement system, as well as American cookbooks, so these figures must be known. Essentially, this means US children must learn two measurement systems, and unless they plan to export items, or become doctors or scientists, they may never fully master SI.

Unless the US government insists on the conversion in products, and teaching in the metric system, it is likely that the US will retain their own measurement system. However, with increasing globalization it makes sense to consider that much of the world, and especially the scientific world, relies on the metric system. Our ability to learn it makes us have that much more in common with our fellow countries.