Bigger Than a Metre
How far is it to the next town? You could say "40,000 metres", but that is a lot of zeros to say, and hard to picture. For long distances, we need a bigger unit.
The kilometre
Put 1,000 metres end to end, and you have one kilometre. Its symbol is km.
So 1 kilometre = 1,000 metres. That next town is 40 km away.
Road signs in most of the world show distances in kilometres. Maps, running races and car journeys use them too.
How far is a kilometre?
A football pitch is about 100 metres long. So 10 football pitches in a row make about a kilometre.
Another way to feel it: an adult walking at a normal pace covers about a kilometre in 12 to 15 minutes. If the school or the shop is a 15-minute walk away, it is about a kilometre from your door.
Some long distances
- A long running race, the marathon, is about 42 km.
- In the Metre lesson we saw that the metre was made by splitting the distance from the North Pole to the equator into ten million parts. That means the distance from the North Pole to the equator is ten million metres, which is about 10,000 km.
- So once around the whole Earth is about 40,000 km.
Those last two numbers are not a lucky chance. They come straight from the way the metre was made.
Try it at home
- With an adult, use a phone's map to find something about 1 km from your home: a shop, a park or a school.
- Walk there and time the walk. Did it take about 12 to 15 minutes?
- Count your steps on the way. How many of your steps make a kilometre?
Words to know
- kilometre - 1,000 metres; its symbol is km. Used for long distances
Big idea
For long distances we use the kilometre, which is 1,000 metres - about 10 football pitches, or 12 to 15 minutes' walk. Because of how the metre was made, the Earth is about 40,000 km around.