Measuring length means finding out how long something is with a ruler.
Line up one end of the object with 0 and read the mark at the other end.
Short things fit in centimetres, longer ones in metres, where 1 m equals 100 cm.
Here you slide a pencil along the ruler to read it, then split centimetres into metres and centimetres.
How to Measure Length?
📏 Use a Ruler!
①Use a ruler with markings
②Align one end of the object with 0
③The mark at the other end is the length
Measuring with a Ruler
12 cm
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Showing how to measure a pencil with a ruler in cm
💡 How to Measure Accurately
①Align one end exactly with 0
②Place ruler parallel to the object
③Read the mark at eye level
cm and m
235 cm
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Converting cm to m and cm
🚶 m is for Big Lengths
①1 m = 100 cm
②Arms spread out is about 1 m
③Long things like a classroom are easier to measure in m
Summary
Length Units
1 m = 100 cm
Relationship between m and cm
Adding Lengths
3 cm + 5 cm = 8 cm
Add same units together
Subtracting Lengths
10 cm - 4 cm = 6 cm
Subtract same units
🎯 Remember!
①cm for short, m for long
②1 m = 100 cm
③Align with 0 to measure
④Add/subtract same units
⑤Estimate first: "About how many cm?"
Examples and Unit Test
Example 1
One ribbon is 14 cm and another is 23 cm. What is their total length?
1
Add the same units (cm) together.
2
14 cm + 23 cm = 37 cm.
▸ 37 cm
When adding or subtracting lengths, calculate with the same unit.
Example 2
How many m and cm is 235 cm?
1
Since 1 m = 100 cm, see how many 100s fit in 235 cm.
2
235 = 200 + 35, so it is 2 m 35 cm.
▸ 2 m 35 cm
Group every 100 cm into 1 m and write it as m and cm.