You have learned a lot about both the metric and the imperial systems of measurement. Now you will look at how to convert within each system and between each system.

This first activity will look at conversions within the metric system.

Think about This:

Before we begin looking at conversions, let's review what you have learned about the metric system.

Length

• In the metric system, the basic unit of length is the metre.
• Other units of length include the millimetre, centimetre, and the kilometre.

Mass

• The basic unit of mass (or weight) in the metric system is the gram.
• Other units of mass include the kilogram and the milligram.

Capacity

• The basic unit of capacity of liquids in the metric system is the litre.
• The other common unit of capacity is the millilitre.

Conversions within the Metric System

There are seven main levels of measure within the metric system. These do not change whether you are talking about length, mass, or capacity. The only thing that changes is the base unit. For each measurement, the levels and base units are:

Notice that no matter what you are measuring, the units have the same prefixes, which are grouped around the base unit (metre, gram, or litre) in the same order.

This is because the metric system is based on groups of ten. For example, there are ten millimetres in a centimetre and 10 centimetres in a decimetre and so on. This makes converting between different metric units very easy!

To convert within the metric system, you multiply or divide by 10, or a power of 10 such as 100 or 1,000. To do this, you move the decimal point to the left or right the required number of places, using zeros as place holders when necessary.

Look at the Metric Conversion Chart below.

The rules are:

1. To convert to a smaller unit, move the decimal point to the right or multiply.

2. To convert to a larger unit, move the decimal point to the left or divide.

Let's try a few examples.

What if you have a lake that is 125,000 centimetres long and you want to know how many kilometres long it is? We can figure it out like this:

Courtesy of Pixabay

When converting from a smaller unit (centimetres) to a larger unit (kilometres), the decimal point moves to the left. Count the number of stairs from centimetres to kilometres. There are five, so you would move your decimal five places to the left. Remember to change the unit to kilometres. Like this:

• 125,000. (Since your number doesn't have a decimal showing, put it at the end of the number and then move it five places.)
• 125,000. becomes 1.25
• Therefore, the lake is 1.25 kilometres long.

Here's another example:

What about if you had a garden that was 34.765 dekametres long and you wanted to know how many millimetres that equals. We can figure this out like this:

Courtesy of Pixabay

When converting from a larger unit (dekametres) to a smaller unit (millimetres), the decimal point moves to the right. Count the number of stairs from dekametres to millimetres. There are four, so you would move your decimal four places to the right. Remember to change the unit to millimetres. Like this:

• 34.765 (Notice that you don't have enough numbers to move the decimal four places. When this happens, we add zeros into the blank spots.)
• 34.7650 becomes 347,650
• Therefore, the garden is 347,650 millimetres long.
  

Try This:

Do the following conversion on your own.

 

Your new puppy weighs 2.75 kilograms. You are interested in knowing his weight in grams. Do the conversion.

Courtesy of Pixabay

Self-check!