Lesson 17 – Imperial & Metric Measurements &
Conversions
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Understanding the Imperial measurement system
Understanding the Metric measurement system
Converting measurements within the same measurement system
Converting measurements to and from Metric and Imperial systems
Imperial and Metric Units
Canada adopted the metric system of measurement in 1971. The metric system is based on
units of 10. We know that 10 mm = 1 cm and that 100 cm = 1 m. Construction (such as
house building etc.) and manufacturing (such as cars or clothes) still use the imperial
system of measurement. Even today people generally refer to themselves in feet, inches
and pounds.
The imperial system has a basic unit of length that is one inch. Each inch is divided up into
1
2
1
16 equal parts. One part is
, two parts is
which can be reduced to .
16
16
8
The most common units of measurement in the imperial system are inches denoted (“), feet
denoted (‘), yards and mile.
Conversion Table
Metric System
10 mm = 1 cm
100 cm = 1 m
1000 m = 1 km
Imperial System
12 inches = 1 foot
3 feet = 1 yard
1760 yards = 1 mile
Equivalent
1 inch is approximately equal to 25.5 mm
1 foot is approximately equal to 30.48 cm
1 yard is approximately equal to 0.9144 m
1 mile is approximately equal to 1.609 km
Example 1
Convert 6 feet to inches.
Solution
6 x 12 = 72 inches
We may know that there are 12 inches in each foot. Here we
have 6 feet, therefore, we have 12 + 12 + 12 + 12 + 12 +12, that
is 12 inches six times, which is 6 x 12.
Example 2
Convert 500 metres to kilometres
Solution
We know that there are 1000 metres in a
kilometre, so 500 m is half of 1000, therefore it is
half of a kilometre.
500  1000  0.5 km
People sometimes have difficulties converting to and from Metric to Imperial systems .
Below is an example of a useful chart to help with conversions.
KNOW and NEED chart
Let us consider our first example of converting 6 feet to inches. The first step is to put the
units you are working with in the chart.
It doesn’t matter which one you write first as long as
they appear in the centre column of the chart
Next we fill in what we know in the “KNOW” column of the chart.
We know 1 foot has 12 inches.
Then in the “NEED” column we can put a 6 beside the feet because that is in the question
and a ? beside the inches because that is what is being asked to find.
The chart represents to equal fractions.
1
6
under the “know” heading and under the
12
?
“need” heading.
Finally to find “?” we cross multiply to find the solution to our question.
Therefore there are 72 inches in 6 feet.
Example 3
Convert 454 feet to yards.
Solution
Therefore is there is approximately 151.3 yard in 454 feet.
Example 4
How many inches are in 300 mm?
Solution
Therefore there are approximately 11.76 inches in 300 mm.
Homework Questions
1. Find the area of the triangle in imperial and metric units.
Part II
2. How many millimetres would represent 14 inches?
3. How many miles would be equal to 3 km?
Part III
1. Convert the following:
a. 36 inches to millimetres
b. 1400 feet to centimetres
2. Find the perimeter in Imperial units and the area in Metric units.
a. a square with sides 5 yards long
b.
3. You are giving an older friend directions to your cottage. You say that it is 325 km to
the cottage. The friend knows they can go 60km/hr. How long will it take them to get
to the cottage?
4. You tell your older friend that it is 100 metres across the bay. They want to know
how many feet that is.
5. Your older friend calls you and says they have a 6 yard by 6 yard tarp they can bring
to cover an open area at your cottage. You know the area of the picnic tables to be
tarped is 48 metres squared. Should your friend bother to bring their tarp because it
is too small?