Video Transcript
Kilometers
In this video, we will learn how to
measure length in kilometers, convert kilometers to meters or mixed units, and
compare lengths in kilometers and meters.
When we’re traveling from one place
to another, we can use kilometers to measure distance. These children are traveling to the
beach. Let’s read the road sign to find
out how many kilometers it is until they reach Sandy Beach. Did you notice the letters km? km
is how we abbreviate kilometers. So it’s 15 kilometers to the
beach. The children are going to stop at
Blue Lagoon on their way to the beach. How many kilometers is it to the
Blue Lagoon?
We can see from the road sign that
next to Blue Lagoon it says the number three. And we know the unit of measurement
is kilometers, so the children are three kilometers away from the Lagoon. A kilometer is equal to 1,000
meters. So if we wanted to write the
distance to the Lagoon in meters, we would have to convert our kilometers into
meters. And we can use this bar model to
help. If one kilometer is equal to 1,000
meters, then three kilometers is equal to 3,000 meters. To convert kilometers to meters, we
have to multiply the amount of kilometers by 1,000. Three kilometers multiplied by
1,000 is 3,000 meters.
When we multiply a number by 1,000,
the digits move three places to the left. And if we want to convert an amount
of meters to kilometers, we do the opposite. We divide the meters by 1,000. When we divide a number by 1,000,
the digits move three places to the right. So if we want to convert the
distance to the beach from kilometers to meters, we would need to multiply 15 by
1,000. When we multiply by 1,000, the
digits move three places to the left. The distance to the beach is 15,000
meters.
We can also use kilometers to
measure the length or height of objects. The height of this mountain is
three kilometers 545 meters. Did you notice that this height has
been given in mixed units, kilometers and meters? And the height of this mountain has
been given in meters, 2,365 meters. If we were asked to compare the
height of these two mountains, we’d need to convert them both to the same units of
measurement. Let’s convert our three kilometers
545 meters into meters.
To do this, we can break the
numbers apart, into kilometers and meters. We don’t need to convert this part
because it’s already given in meters. We know that one kilometer is equal
to 1,000 meters, so three kilometers is equal to 3,000 meters. Now, all we need to do is add our
parts back together again. 3,000 plus 545 is 3,545 meters. Now that both of our heights are
given in the same unit of measurement, we can compare them. Three kilometers 545 meters is
greater than 2,365 meters. This is the tallest mountain.
The children have almost reached
the beach. It’s only 500 meters until they get
there. How many kilometers is it to the
beach? We know that 1,000 meters equals
one kilometer. We also know that 500 is half of
1,000. So 500 meters is equal to half a
kilometer. A quarter of 1,000 is 250, so 250
meters is equal to a quarter of a kilometer. And 750 meters would be equal to
three-quarters of a kilometer.
So far, we’ve learned that one
kilometer is equal to 1,000 meters. We’ve learned that to convert from
kilometers to meters, we multiply the amount of kilometers by 1,000. And to convert from meters to
kilometers, we need to do the opposite, divide by 1,000. We’ve also learned that when we’re
comparing distances or height or lengths, we need to compare the same units. If a measurement is given in mixed
units, we may have to convert.
We’ve also learned that half a
kilometer is equal to 500 meters, a quarter of a kilometer is equal to 250 meters,
and three-quarters of a kilometer is equal to 750 meters. Let’s try some questions now to
help us practice what we’ve learned about kilometers.
Which of the following is a true
statement? 1,000 kilometers is equal to one
meter. 100 kilometers is equal to one
meter. 1,000 meters is equal to one
kilometer. Or 100 meters is equal to one
kilometer.
We know that one kilometer is equal
to 1,000 meters. So we can say that this statement
is a false statement. The units of measurement are the
wrong way round. It should say 1,000 meters is equal
to one kilometer. The second statement is also
false. 100 kilometers is not equal to one
meter. How about this statement? 1,000 meters is equal to one
kilometer. This is true. We know that this statement is also
false because there are 1,000 meters in one kilometer. The statement which is true is
1,000 meters is equal to one kilometer.
Complete: 6,521 meters is equal to
what kilometers and what meters?
In this question, we’re given a
measurement in meters, and we have to write it as an equivalent amount of kilometers
and meters. Let’s use a part–whole model to
help. The whole amount is 6,521
meters. And we have to write this as an
amount in kilometers and meters. We know that one kilometer is equal
to 1,000 meters. So if we partition 6,521 into 6,000
and 521, this will help us convert our 6,000 meters into kilometers. To convert an amount of meters to
kilometers, we have to divide by 1,000. 6,000 divided by 1,000 equals
six.
We converted our 6,000 meters into
six kilometers. So the missing numbers are six and
521. 6,521 meters is equal to six
kilometers and 521 meters. We’ve completed the equation. 6,521 meters is equal to six
kilometers and 521 meters.
Complete: What meters is equal to
three kilometers and 352 meters.
In this question, we’re given a
measurement in mixed units, three kilometers and 352 meters. We have to write this as an amount
in meters. And we’ve been given a part–whole
model to help. We’re being asked to find the
amount in meters. The amount we’ve been given has
been partitioned or broken apart into an amount of kilometers, there are three, and
an amount of meters, 352. 352 is already written in meters,
so we just need to convert the amount in kilometers to an amount in meters.
If one kilometer is equal to 1,000
meters, how many meters are there in three kilometers? To convert from kilometers to
meters, we have to multiply our amount of kilometers by 1,000. So one kilometer multiplied by
1,000 equals 1,000 meters. So to convert three kilometers to
meters, we just need to multiply our three kilometers by 1,000. Three kilometers is equal to 3,000
meters.
Now all we need to do is add our
two parts back together again, 3,000 meters plus 352 meters. The missing number is 3,352. 3,352 meters is equal to three
kilometers and 352 meters.
Write in meters: five and a half
kilometers.
In this question, we have to
convert five and a half kilometers into meters. If one kilometer is equal to 1,000
meters, then five kilometers is equal to 5,000 meters. Now all we need to do is work out
what half a kilometer is equal to in meters. What is half of 1,000? 5,000 plus 500 is 5,500 meters. Five and a half kilometers is equal
to 5,500 meters.
Which is greater, 2,358 meters or
three kilometers?
In this question, we’re being asked
to compare two measurements, 2,358 meters and three kilometers. We’re being asked to compare two
different units of measurement, meters and kilometers. When we’re comparing two
measurements, it helps if we compare them using the same unit of measurement. We could convert our amount in
kilometers into meters. If one kilometer equals 1,000
meters, we just need to multiply our kilometers by 1,000.
Three multiplied by 1,000 is
3,000. 2,358 is less than 3,000. Comparing two measurements with the
same units is much easier. So if 2,358 meters is less than
three kilometers, then three kilometers is greater than 2,358 meters. Three kilometers is greater.
So what have we learned in this
video? We’ve learned that one kilometer is
equal to 1,000 meters. We’ve also learned how to convert
kilometers to meters and meters to kilometers. We learned that half a kilometer is
equal to 500 meters and a quarter of a kilometer is equal to 250 meters. And finally, we learned that when
we’re comparing lengths or distances, we need to compare the same units of
measurement.
