2.1.1

Length

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Length

Length means the measurement of how long something is or the distance between two places. Metres, centimetres, millimetres and kilometres are all units of length.

Units of length

Units of length

  • In measurement, we use the word unit to describe what measurement we are using.
    • Metre, centimetre, millimetre and kilometre are all units of length.
  • We write units after the number, using lower case letters.
    • 5 m (five metres).
    • 20 cm (twenty centimetres).
    • 340 mm (three-hundred and forty millimetres).
    • 10 km (ten kilometres).
Relations between units

Relations between units

  • If you look at your ruler, you will see it shows some units of length.
  • Most rulers show centimetres (cm) and millimetres (mm).
  • You can see that millimetres are smaller and centimetres are bigger.
    • There are 10 millimetres in 1 centimetre.
    • There are 100 centimetres in 1 metre.
Mixed units

Mixed units

  • Sometimes an object won't have an exact measurement in one unit.
    • For example, a car is measured to be 4 and a half metres long.
  • That means the length of the car is the same as 4 metres plus 50 centimetres, which is half a metre.
  • We write this as 4 m 50 cm or 4 1/2 m.
Measuring objects

Measuring objects

  • You should use millimetres (mm) to measure small objects like the tip of a pencil.
  • You should use centimetres (cm) to measure medium-sized objects like books.
  • You should use metres to measure large objects like cars and classrooms.
  • You should use kilometres to measure very large distances, for example between towns and cities.
Jump to other topics
1

Year 3 - Number

1.1

Number & Place Value

1.1.1Multiples1.1.2Counting in Multiples1.1.3Recognising Three-Digit Numbers1.1.4Finding 10 More or Less than a Number1.1.5Finding 100 More or Less than a Number1.1.6Ordering & Comparing Numbers up to 1,0001.1.7Writing & Reading Numbers1.1.8Representing Numbers
1.2

Addition & Subtraction

1.2.1Mental Addition & Subtraction1.2.2Column Method1.2.3Estimating Calculations1.2.4Inverse Operations1.2.5Missing Number Problems1.2.6Real-Life Problems
1.3

Multiplication & Division

1.3.1Times Tables1.3.2Using Times Tables1.3.3Multiplying Numbers1.3.4Missing Number Problems1.3.5Real-Life Problems
1.4

Fractions

1.4.1Tenths1.4.2Fractions1.4.3Fractions Equal to a Whole1.4.4Equivalent Fractions1.4.5Fractions of Shapes1.4.6Fractions of Amounts1.4.7Add & Subtract Fractions1.4.8Compare & Order Fractions
2

Year 3 - Measurement

2.1

Length

2.1.1Length2.1.2Comparing Lengths2.1.3Add & Subtract Lengths2.1.4Perimeter
2.2

Mass

2.2.1Mass2.2.2Comparing Masses2.2.3Add & Subtract Masses
2.3

Volume & Capacity

2.3.1Volume & Capacity2.3.2Comparing Volumes2.3.3Add & Subtract Volumes
2.4

Money

2.4.1Money2.4.2Counting Money2.4.3Adding & Subtracting Money
2.5

Time

2.5.1Units of Time2.5.2Clocks2.5.3Telling the Time2.5.4Time of the Day2.5.512-Hour & 24-Hour Clocks2.5.6Measuring Time
3

Year 3 - Geometry

3.1

Angles

3.1.1Angles in Degrees3.1.2Types of Angle
3.2

Properties of Shapes

3.2.12D Shapes3.2.23D Shapes
3.3

Straight Lines

3.3.1Straight Lines3.3.2Parallel & Perpendicular Lines
4

Year 3 - Statistics

4.1

Statistics

4.1.1Statistics4.1.2Pictograms & Bar Charts
5

Year 4 - Number

5.1

Number & Place Value

5.1.1Counting in Multiples5.1.2Recognising Four Digit Numbers5.1.3Find 1,000 More or Less than a Number5.1.4Negative Numbers5.1.5Ordering & Comparing Numbers Over 1,0005.1.6Representing Numbers5.1.7Rounding Numbers5.1.8Roman Numerals
5.2

Addition & Subtraction

5.2.1Written Methods for Adding Large Numbers5.2.2Written Methods for Subtracting Large Numbers5.2.3Estimation & Inverse Operations5.2.4Solving Two-Step Problems
5.3

Multiplication & Division

5.3.1Times Tables5.3.2Using Times Tables5.3.3Multiplication Rules5.3.4Column Method5.3.5Factors
5.4

Fractions & Decimals

5.4.1Identifying Equivalent Fractions5.4.2Adding & Subtracting Fractions5.4.3Hundredths5.4.4Decimals5.4.5Converting Between Decimals & Fractions5.4.6Rounding Decimals5.4.7Ordering Decimals
6

Year 4 - Measurement

6.1

Units

6.1.1Metric Measurements6.1.2Adding & Subtracting Money
6.2

Time

6.2.1Converting Units of Time6.2.2Changing the 12-Hour Clock to the 24-Hour Clock6.2.3Changing the 24-hour Clock to the 12-Hour Clock
7

Year 4 - Geometry

7.1

Properties of Shapes

7.1.1Symmetry7.1.2Types of Triangle7.1.3Quadrilaterals
7.2

Perimeter & Area

7.2.1Perimeter7.2.2Area
7.3

Position & Direction

7.3.1Coordinates7.3.2Translation
8

Year 4 - Statistics

8.1

Statistics

8.1.1Types of Data8.1.2Pictograms & Bar Charts8.1.3Line Graphs

Practice questions on Length

Can you answer these? Test yourself with free interactive practice on Seneca — used by over 10 million students.

  1. 1
    Which unit of length should you use to measure a classroom?Multiple choice
  2. 2
    Which unit of length should you use to measure a grain of rice?Multiple choice
  3. 3
    Which unit of length should you use to measure the length of a shoe?Multiple choice
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Compare & Order Fractions

Comparing Lengths