teaching the metric system
Advice, Teacher Life

Teaching the Metric System: Why it is SO hard!

Have you struggled with teaching the metric system to your students? You aren’t alone! I reached out to a professional math tutor to help shed some light on why it is so hard to teach metric measurement in the United States.

Learning math is not entirely different from learning language, and metric units must be introduced as early as possible so students have a better understanding of the dual systems we use in the United States. My students have typically had little (or no) exposure to SI measurement in 5th grade, so it makes the task of teaching proper scientific measurement incredibly difficult.

Every year I feel like I spend weeks trying to teach students proper scientific measurement, only for them to continuously struggle with the concept for the next two years they are with me. I believe the problem lies in the fact that we are one of only three countries in the world to continue using the archaic customary system.

I hope you enjoy this fascinating look into the history of measurement!

teaching the metric system steam stem
Be sure to check out my metric measurement STEAM activity at the bottom of the post!

Metricating the United States: Long Overdue

Guest Post by Sindu Bharathi from Online Math Tutor Now

Historical Context

The Metric System (or the SI System) first came to practical use in 1799 in France. To
standardize measurements, get rid of the old traditions and purge the religious influences
on the calendar, the French Revolutionaries put the Metric System into place.

Fun Fact: The French Revolutionaries even created metric time with 100 seconds per minute, 100 minutes per hour, and 10 hours per day, but it didn’t work out very well.

teaching the metric system

Before the French Revolution, there were millions of measurements used around the world. Weights and measures varied from village to village and town to town based on the unique standards they created.

In 1790, a panel of French scientists, including Laplace and Lagrange, were appointed to investigate weights and measures. A new system of weights and measures should have a decimal radix, the unit of length should be based on a fractional arc of a quadrature of Earth’s meridian, and the unit of weight should be that of a cube of water whose dimension was a decimal fraction of the unit of length.

On April 7, 1795 the Metric System was formally defined in French law.

  • The metre for length
  • The litre for volumes of liquid
  • The gramme for mass

Fun Fact: The U.S. Customary System is derived from Britain’s Imperial System based on traditional measures that have been used for centuries, but even Britain formally switched to metric in 1965.

Metric Measurement

Is metric the perfect system for measurements? Certainly not! The metric system is just as arbitrary as the Customary System. But metric is the most logical system based on current standards. Units like the Newton and millimeter are certainly better than trying to determine pound force or measure a small object using 0.0393701 inch.

“Every measurement system we have is arbitrary. The fact that our [metric] number system is base 10 is arbitrary. The only unit system that wouldn’t be arbitrary would be one based entirely on universal constants. G=1, ϵ0 = 2. That kind of thing.”

Johnny Coleman, Physicist from California Polytechnic University

Many teachers I have spoken with agree that metric makes much more sense and is easier to learn. Because it coincides with the number system we use, students find it easier to learn.


Teaching temperatures in metric helps the teachers introduce negative integers, whereas in the customary units, the fractional increments make it harder to convert. Conversions between different units in the metric system uses simple increments of ten while the English system uses different conversion factors that are confusing and rely on rote memorization of arbitrary units.

For example:

Customary Conversions

1 yard = 3 feet

1 foot = 12 inches

1 gallon = 128 ounces

Metric Conversions

1 meter = 100 centimeters

1 liter = 1000 milliliters

1 kilogram = 1000 grams

See a difference? The metric use of increments of ten with corresponding prefixes across all metric standards is a clean and logical way to measure. It makes conversions between units simple to learn and teach.

teaching the metric system

“The fractional increments are so hard for kids to understand. When using standard measurements, many of them tend to think each mark is .1 — so instead of measuring 2 and 1/8, they’ll write 2.1. And then adding and subtracting is a huge hassle. It’s super easy to add 4.1 + 2.6 mentally but to add 3 1/4 + 5 3/16 requires so much more time and effort. I wish we’d switch and be like the rest of the world!” said one teacher I spoke with.

Metric measurement is the standard in the scientific community around the world. Also, there is the fact that every country in the world except the United States, Myanmar, and Liberia use metric as their official system of measurements.

The U.S. could have (and SHOULD HAVE) been metricated earlier.

The Metric System in America

In 1790, The French Government sent a proposal to establish the universal measure of length as the metre to Britain and the United States. Both countries rejected the proposal because each of them wanted to define the metre according to a major latitude passing through their country. Pride and patriotism interfered with common logic.

Fun Fact: In 1973, Secretary of State Thomas Jefferson requested that artifacts from the French Government be sent to the United States in order to consider the introduction of a uniform system of weights in the US. The French sent Joseph Dombey, a botanist and a explorer with a kilogram prototype. Tragically, his ship was hit by a giant storm and he was captured by a group of pirates, eventually perishing in their captivity. Hence, the standard kilogram never reached the United States.

Shortly after the Civil War, the Metric Act of 1866 was passed by the US Congress, protecting the use of the Metric System in commerce from lawsuits, and also provided an official conversion table from US Customary units.

Next followed the Metric Conversion Act of 1975, which declared the Metric System as “the preferred system of weights and measures for United States trade and commerce,” but permitted the use of the United States Customary System in all activities. It also established the United States Metric Board to plan, coordinate, and educate the American people for the Metrication of the United States.

Later, the metrification board was abolished in 1982 by President Ronald Reagan due to resistance from the public and industries.

While it is true that switching over was harder in the United States than other countries due to advanced industrialization and development, it wouldn’t have collapsed the economy or caused a three month riot, as it did in Brazil!

Why are we still resisting the change?

The US has already converted to metric in many disciplines like science, technology, military, and even many consumer products are starting to use the Metric System of Measurements.

metric measurement in the united states

So what is stopping the U.S. from making the switch? These are the two reasons cited most often.

  1. Replacement costs for the government and industries and 2) the change in mindset of the people.

For example, Britain officially metricated its measurements in 1965. So, do the people of Britain suddenly think and speak in metric? Of course not. While they are officially metric on paper, people continue to use the customary system in day to day life although they don’t teach customary in schools anymore. The goal is that the customary system eventually become extinct as time passes. Here is a respondent’s comment from Saudi Arabia, where they have been using metric since 1970.

“I grew up with metric and thus metric is logical for me. I have to convert to imperial.
For instance I can see 1 meter, but have to work it out to foot.”

For a new system to replace the existing system, the most effective way is to legally enforce and encourage the new one and force the old one to fade away with time. While the U.S. encourages business and the public to use metric, it doesn’t enforce it. People do not have the need or the drive to make it happen. It will not be possible to make the Metric System mainstream in the Unites States without a change in the mindset of an entire population, so it is important to acquaint the current populace of students with the system from the time they begin learning measurement in school.

About the Author

online math tutor

Sindu Bharathi is an online math tutor working with High School and University students across the world. You can find out more on her website, blog and Facebook!





Need an idea to help students practice and apply metric measurement? Look no further than my STEAM Paper Planes Trashtivity….I mean activity! Recycle your old copies with this activity bundle while your students have a blast learning, analyzing, and graphing.

STEAM Metric Measurement Paper Airplanes

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