Lesson · Grade 10 · Workplace Mathematics
Imperial length units: inches, feet, yards and miles
- Grade 10
- Workplace Mathematics
- 2 min 13 s
- British Columbia
- BC10-MA-51
A ruler, a tape measure and a road sign show that 12 inches make a foot, 3 feet make a yard and 5280 feet make a mile. A board 100 inches long is then worked out as 100 ÷ 12 = 8 remainder 4, which is 8 ft 4 in, checked as 8 × 12 + 4 = 100, and the video shows why 8 ft 4 in is about 8.33 ft, not 8.4 ft.
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In one sentence
The question this lesson answers
A wooden board is 100 inches long. How long is that in feet and inches?
Imperial units are an older system that some places still use. The common units of length are inches, feet, yards and miles.
Transcript
What the lesson says
A wooden board is 100 inches long. How long is that in feet and inches?
Imperial units are an older system that some places still use. The common units of length are inches, feet, yards and miles.
Here is a ruler marked in inches. One inch is exactly 2.54 centimetres.
This ruler is 12 inches long, and 12 inches make 1 foot.
This tape measure is marked in feet. Count them: 1, 2, 3. Three feet make 1 yard.
Some road signs give long distances in miles. One mile is 5280 feet.
To change the inches into feet, divide by 12, because 12 inches make 1 foot.
12 times 8 is 96. 12 times 9 is 108, which is too big. So 12 goes into 100 eight times.
100 take away 96 leaves 4, which is called the remainder. So 100 divided by 12 is 8, remainder 4.
Mark off whole feet along the board: 1, 2, 3, 4, 5, 6, 7, 8. The 4 inches left over are the remainder.
So 100 inches is 8 feet 4 inches.
Check: 8 times 12 is 96, and 96 plus 4 is 100.
A common mistake is to read 8 feet 4 inches as 8.4 feet. They are not the same.
A foot has 12 inches, not 10, so 4 inches is 4 twelfths of a foot, about 0.33 feet.
So 8 feet 4 inches is about 8.33 feet, not 8.4 feet.
To recap: divide the inches by 12. The whole number is feet, and the remainder is inches.
Curriculum
Where this fits
- British Columbia, Grade 10
Workplace Mathematics 10, Geometry and measurement: metric and imperial measurement and conversionsBC10-MA-51
The outcomes and strands follow the British Columbia curriculum.
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