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### Course: 5th grade > Unit 14

Lesson 2: Converting metric units- Converting units: metric distance
- Converting units: centimeters to meters
- Convert units (metrics)
- Metric units of mass review (g and kg)
- Metric units of length review (mm, cm, m, & km)
- Metric units of volume review (L and mL)
- U.S. customary and metric units

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# U.S. customary and metric units

This video dives into the world of measurement units, distinguishing between U.S. customary units and metric units. It explores how these units measure different aspects such as length, weight, mass, and volume. Created by Sal Khan and Monterey Institute for Technology and Education.

## Want to join the conversation?

- The (British) imperial system or the "US customary" system currently used in the US is so outdated. United States is one of three countries in the world that still uses these messy English units, alongside Myanmar and Liberia. It's the measurement system of the old world - these English units date back at least to the middle ages! Even the Brits have gone metric!

So what's stopping the US from adopting the International System of Units or the "metric system" as its official and primary system of measurement? Is it the cost of the transition? Or is it the American urgent need for "individuality"?

The metric system is 10 times better!(23 votes)- I'll posit that Americans are, generally speaking, happy with the imperial system. They don't want to learn the new system, because this one works fine for them. Also, road signs and gas stations currently use miles. While retrofitting gas stations to use metric probably would be cheap (though there isn't much demand for them to do so), changing old road signs from using miles to kilometers would be very expensive and would require a complete revamp of our road systems.(11 votes)

- Why is metric better?(10 votes)
- Metric has more value and responsibilities. It is common around the world. It is the main system to measure. It used in India,Germany.Russia,Netherlands and many more sights in the world. Our Us Customary System has less responsibilities cause of the metric system(12 votes)

- How did the U.S. get this separate system of measurement in the first place?

And why did the U.S. government decide not use the metric system or SI units?(11 votes)- The metric system came along after the system the US still uses. Years ago, most other countries went metric. The US tried to, but Americans just wouldn't go along.(8 votes)

- why is it that the United States does not use the metric system?(3 votes)
- In the United States, students have been learning both systems for at least 40 years. And both systems are pretty widely understood and used in the U.S.

Becasue the US Government has limited power to demand that everyone use only the decimal system, both systems have continued to be used because that it what people choose to do.(12 votes)

- At4:44-5:03, Sal mentions that there are two measurements called "ounces." how did something like this happen? I know that in the metric system, the units of mass, volume, and distance are connected, for one cubic centimeter = one milliliter, and the gram was originally calculated as the mass of one milliliter of water. However, I want to know if there is any connection between fluid ounces (for volume) and ounces (for weight).(4 votes)
- Historically, a fluid ounce was equal to the volume of one ounce of a liquid (water, beer, wine, etc.) - but this meant that the actual volume of 1 fluid ounce would differ from one substance to another.

At present, 1 oz of pure water is roughly equal to 1 fl oz of pure water. If you measure 1 fl oz of other liquids, however, they may or may not weigh 1 oz.

Hope this helps!(4 votes)

- how is U.S customary units and metric units different?(3 votes)
- The “Imperial System” is based on fractions, while metric is based on decimals. Once you get that, a lot of the confusion goes away. This is why Americans tend to do things in fractions, such as “quarter mile”, or “half inch”, or “third of a pound”.(1 vote)

- Why is the US customary system based on ambiguous numbers like 3, 12, and 1280?(5 votes)
- There not ambiguous, but the customary measurements are all sorts of orquard and outdated.

However a small benifit is that a high proportion of natural numbers smaller than numbers like 12 and 360 are factors of those numbers, unlike 10 and 1000.

10: 2, 5

12: 2, 3, 4, 6

1000: 16 factors, lowest few being: 2, 4, 5, 8, 10

360: 24 factors, including 2, 3, 4, 5, 6, 7, 8, 9, 10(0 votes)

- what is the difference between deci and deca in the metric system of measure(1 vote)
- Deci means one-tenth (1/10) of the base unit.

Deca means ten times (10x) the base unit.

So for example if the base unit is meters.

1 decimeter is 1/10 of a meter.

1 decameter is 10 meters.

Hope my explanation was helpful :)(6 votes)

- how is a decameter some times always one i though it was some 2(3 votes)
- Can someone tell me why the U.S prefers different units?(2 votes)

## Video transcript

We're asked to sort the
following units of measurement into two categories:
U.S. customary units and metric units. So these are just two different
systems. You'll get more and more familiar
with them. Then indicate whether each unit
measures length, weight, mass, or volume. Let's do the first. Let's see
which of these are U.S. customary unit versus
metric units. So the liter is a metric unit. You would use it in
the metric system. A gallon is a U.S.
customary unit. We've been dealing with that. If you fill your gasoline in
Europe, you're going to be filling it in terms of liters. In the U.S., you're going
to be filling it in terms of gallons. And we're going to talk about
whether they're units of volume and whatnot
in a little bit. Decigram, that is
metric system. In general, whenever you see
these prefixes, deci, centi, kilo, you're dealing with
the metric system. No one ever talks about
a kilopound. I guess you could, but no one
really talks about it. Same thing, millimeter. This is metric system. A gram is metric system. Meter is metric system. The foot is a U.S.
customary unit. We'll talk about whether it's
distance or any of that in a little bit. Kilogram, once again,
it is metric units. In case you haven't gotten what
I'm doing here, blue for metric, red for U.S. customary
units, or I guess magenta. Centiliter, that is metric. Centimeter, meters are metric. And notice we have the
prefix in both cases. Centi means 1/100. Cup, that is U.S.
customary units. I have to do that
in the magenta. Cup, U.S. customary units. Meter, that is the
metric system. Pound, U.S. customary units. It's getting a little tedious. Inch, same thing, that's what
we use in the U.S. Ounce, we use that in the U.S. And then
the yard, we also use that in the U.S. Now we've divided them up. All the magenta ones are used
in the U.S. All of the blue ones are used really in the
rest of the world, and actually some places in
the U.S. as well. I think a lot of the world is
frustrated that the U.S., that we're not all converted to this
because the metric system is actually a little
bit more logical. It's easy to just figure out
what it's saying, and we'll deal with that in more
detail in the future. Now the next thing we to
figure out is whether something is a measure of
length, weight/mass-- and they're not exactly
the same thing. Mass is how much of a substance
you have. Weight is how much force with
which gravity is pulling on that mass. And it would change depending
on what planet you're on. But on Earth, they tend to be
used interchangeably, so we'll use it roughly interchangeably
here. And then you have volume,
or how much space something takes up. So this is distance. This is moving in
one dimension. Mass is how much
stuff there is. Weight is how much the force
that stuff is pulled on, on a planet, by gravity, or I
guess a star anywhere. And volume is how much space
does that stuff take up. Now let's think about it. Liter is volume. This right here is volume. How much space do you take up. Gallon is also volume. That's in the U.S. And in
Europe, or in the metric system, it would be a liter. That's a gram. Gram is a unit of mass. So decigram just means
1/10 of a gram. Millimeter. Meter is a unit. Meter right here, that is the
unit of distance or of length. Millimeter, milli means
1/1,000 of a meter. Foot, that is also
a unit of length. Kilogram, that just
means 1,000 grams. Kilo means a thousand. Gram, we already said,
is a unit of mass. Centiliter, that means
1/100 of a liter. Liter, we already figured out,
is a unit of volume. Centimeter, we already
figured out. Meter is a unit of length. Centimeter means 1/100
of a meter. So this is a unit of length. Cup, we've seen multiple
times already. It is a unit of volume,
how much space does something take up. Meter, that is length. We've seen it multiple
times already. Pound, that is actually
a unit of weight. An inch is a unit of length. We're all familiar with it. An ounce-- you have to be
careful here-- if someone just has an ounce, that is
1/16 of a pound. It as a unit of weight. If it was written fluid ounce,
then we'd be talking about 1/16 of a pint, and then it
would be a unit of volume. But since it's just ounce,
it's a unit of weight, 1/16 of a pound. And then finally, a yard
is a unit of length. And we are done.