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Grade 2 (age 7-8)

grade 2 Length Measurement

Measuring length means finding out how long something is with a ruler. The ruler has a mark every 1 cm, so you line up one end with 0 and read the mark at the other end. Short things like a pencil or eraser fit in centimetres, longer ones like a blackboard or your height in metres, and 1 m equals 100 cm. Slide the pencil on the ruler to read it, then split centimetres into metres and centimetres.

How do we measure length?

📏 Measure with a ruler
①Use a ruler with marks on it
②Line up one end of the object with 0 on the ruler
③The mark at the other end tells you the length

Measuring with a ruler

12 cm
💡 Measuring carefully
①In the picture, the left end of the pencil is lined up with 0
②The ruler has a mark every 1 cm and a number every 5 cm
③The mark at the right end of the pencil is its length
④Keep the ruler right along the object and read the mark from straight above

Centimeters and meters

235 cm
🚶 Use meters for long lengths
①1 m is 100 cm
②In the picture, the gold part shows the meters and the blue part shows the centimeters left over
③Your arms stretched wide are about 1 m
④Long things like a classroom are easier to measure in meters

Wrap-up

Units of length
1 m = 100 cm
How meters (m) and centimeters (cm) are related
Adding lengths
3 cm + 5 cm = 8 cm
Add lengths that use the same unit
Subtracting lengths
10 cm - 4 cm = 6 cm
Subtract lengths that use the same unit
🎯 Remember
①Short lengths are measured in cm, and long lengths in m
②1 m is 100 cm
③Line up one end with 0 on the ruler
④When adding or subtracting lengths, use the same unit

Examples and unit check

Example 1
One ribbon is 14 cm long and another is 23 cm long. How long are they together?
1
Add the lengths in the same unit (cm).
2
14 cm + 23 cm = 37 cm.
▸ 37 cm
When adding or subtracting lengths, work in the same unit.
Example 2
How many meters and centimeters is 235 cm?
1
Since 1 m = 100 cm, see how many 100 cm fit into 235 cm.
2
235 = 200 + 35, so it is 2 m 35 cm.
▸ 2 m 35 cm
Every 100 cm makes 1 m, so write the length in m and cm.
Unit check
How many centimeters is 1 m 50 cm?
①15 cm
②105 cm
③150 cm
④1500 cm
▸ ③ 150 cm
1
1 m = 100 cm.
2
100 cm + 50 cm = 150 cm.
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