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# The Metric System

### The Metric System

The Metric System is a system of units of measurement, which is used all over the world.

There are **two different systems** for measuring length, mass and capacity

First of all, what do we mean by **length**?

What do we mean by **mass**?

And what do we mean by **capacity**?

So there are two systems for measuring length, mass and capacity

The metric system The imperial system

The metric system uses units like...

metres, kilometres, grams, kilograms, litres, millilitres etc.

The imperial system uses units like...

yards, miles, pounds, stone, gallons etc.

True or false? *Most countries in the world use the imperial system.*

True or false? *Both the metric system and the imperial system are widely used in the UK and in the US.*

This lesson will focus on the metric system

Most countries in the world use the metric system (although the imperial system is also widely used in the UK and in the US).

How many metres are in a kilometre?

How many grams are in a kilogram?

What do you think "kilo" means?

A) Metre B) Gram C) $1,000$

"Kilo" means $1,000$

There are $1,000 \space m$ in a **kilo**metre.
There are $1,000 \space g$ in a **kilo**gram.

How many **metres** are there in 3 kilometres?

How many **grams** are there in 4.5 kilograms?

How many **kilometres** is $14,000 \space m$?

Now, how many millimetres are in a metre?

How many millilitres are in a litre?

What do you think "milli" means?

A) $1,000$ B) $1,000th$

"Milli" means $1,000th$ or $\frac{1}{1,000}$

1 **milli**metre is $1,000th$ of a metre or $\frac{1}{1,000}m$
1 **milli**litre is $1,000th$ of a litre or $\frac{1}{1,000}l$

How many **millilitres** are there in 5.6 litres?

How many metres are $8,500 \space mm$?

How many millimetres are in a centimetre?

So there are $10 \space mm$ in a centimetre. How many centimetres are in a metre, then?

What does "centi" mean then?

A) $100$ B) $100th$

How many centilitres are in a litre?

"Centi" means $100th$ or $\frac{1}{100}$

1 **centi**metre is $\frac{1}{100}m$
1 **centi**litre is $\frac{1}{100}l$

How many **centimetres** are there in 4 metres?

Summary! So the metric system is built up around basic units

Metres, grams and litres

"Kilo" means $1,000$

1 kilometre is $1,000 \space m$ 1 kilogram is $1,000 \space g$

"Milli" means $1,000th$

1 millimetre is $\frac{1}{1,000}m$ 1 millilitre is $\frac{1}{1,000}l$

"Centi" means $100th$

1 centimetre is $\frac{1}{100}m$ 1 centilitre is $\frac{1}{100}l$

Actually there are many more units in the metric system

They all relate to **metres**, **grams** and **litres** as basic units though.