Measuring Length up to 10 m
Primary 1 · Mathematics
Measuring Length up to 10 m
Lesson 4 of 5
12 min
Let's begin
At break the children bring two skipping ropes outside.
Umutoni's rope is 7 m long. Byiringiro's rope is 9 m long.
Everybody wants the longer rope. Who has it?
Today you will compare lengths written in metres.
Look at the numbers only when the unit is the same.
7 m and 9 m both use metres. So you can compare them.
9 is more than 7. So 9 m is longer than 7 m.
Byiringiro has the longer rope.
Careful! Gatete's path is 8 steps. Ishimwe's path is 5 m.
8 is more than 5. But you cannot say Gatete's path is longer.
Steps and metres are not the same unit.
Measure both paths in metres. Then compare the numbers.
Three ropes lie on the grass.
| Whose rope | Length |
|---|---|
| Keza | 3 m |
| Habimana | 6 m |
| Mutesi | 9 m |
Put the numbers in order: 3, 6, 9.
The shortest rope is Keza's rope, 3 m.
The longest rope is Mutesi's rope, 9 m.
Habimana's rope sits in the middle.
Write the m after every number. 3 m, 6 m, 9 m.
Worked example
Mutesi's 9 m rope and Habimana's 6 m rope.
Step 1 Find the bigger number: 9.
Step 2 Take away the smaller number: 9 − 6 = 3.
Step 3 Put the m back: 3 m.
Mutesi's rope is 3 m longer than Habimana's rope.
Careful! Do not add here. Adding gives 15, and no rope on the grass is that long.
Tip
Same unit, then compare
Metres go with metres. Steps go with steps.
If the units are different, measure again before you choose.
Watch: which is longer, 4 m or 6 m?
Do each one, then tap Show answer to check.
Which is longer, 4 m or 8 m?
Answer: 8 m. 8 is more than 4.
Which is shorter, 10 m or 6 m?
Answer: 6 m. 6 is less than 10.
Put these in order, shortest first: 5 m, 2 m, 9 m.
Answer: 2 m, 5 m, 9 m. Order the numbers, then write the m.
Uwase's rope is 8 m. Keza's rope is 5 m. How much longer is Uwase's rope?
Answer: 3 m. 8 − 5 = 3, then put the m back.
Gatete says his 7 steps beat a wall of 7 m. Is he right?
Answer: no. Steps and metres are different units. Measure his path in metres first.
What you learned today
Quick check
Which is longer, 5 m or 9 m?
