📏 Detailed Explanation of Comparing and Converting Metric Units of Length

In Year 3 Maths, you learn how to compare and convert metric units of length. This means you work with different units like millimetres (mm), centimetres (cm), metres (m), and kilometres (km) to measure how long or how far something is.

🔍 What Are Metric Units of Length?

Metric units are the way we measure length in the UK. The main units you will use are:

  • Millimetres (mm): Very small, used for tiny things like the width of a pencil.
  • Centimetres (cm): Bigger than millimetres, used for things like a book or your hand.
  • Metres (m): Used for bigger things like a door or a classroom.
  • Kilometres (km): The biggest of these, used to measure long distances, like from your house to the park.

⚖️ How to Compare Metric Units of Length

To compare lengths, you need to know how big each unit is. Here is how they stack up:

  • 10 millimetres = 1 centimetre
  • 100 centimetres = 1 metre
  • 1000 metres = 1 kilometre

This means:

  • A centimetre is 10 times bigger than a millimetre.
  • A metre is 100 times bigger than a centimetre.
  • A kilometre is 1000 times bigger than a metre.

🔄 How to Convert Metric Units of Length

When you convert, you change one unit into another, like changing centimetres into metres. Use these steps:

  1. Remember the conversion facts:
    – 10 mm = 1 cm
    – 100 cm = 1 m
    – 1000 m = 1 km
  2. To convert smaller units to bigger units, divide:
    – Example: To change 200 cm into metres, divide 200 by 100.
    – 200 cm ÷ 100 = 2 metres.
  3. To convert bigger units to smaller units, multiply:
    – Example: To change 3 m into centimetres, multiply 3 by 100.
    – 3 m × 100 = 300 centimetres.

✏️ Examples to Practice

  • Convert 5000 millimetres to metres:
    • First, remember 1000 mm = 1 m.
    • Divide 5000 ÷ 1000 = 5 metres.
  • Convert 7 kilometres to metres:
    • 1 km = 1000 m.
    • Multiply 7 × 1000 = 7000 metres.

🧠 Study Tips for Comparing and Converting Metric Units

  • Use a place value chart for metric units so you can see how many tens or hundreds you are working with.
  • Remember to always check if you need to multiply or divide.
  • Try measuring objects around your home using rulers or tape measures to practise recognising the units.
  • Use real-life examples, like how far you walk in a day, to understand kilometres and metres.

By practising these steps, you will become confident at comparing and converting metric units of length in Year 3 Maths! 🎉

📝 20 Examination-Style Questions on Comparing and Converting Metric Units of Length

Here are 20 examination-style questions to help Year 3 students practise comparing and converting metric units of length in Maths. These questions focus on comparing centimetres, metres, and millimetres, as well as converting between these units.

❓ Questions

  1. Which is longer: 150 centimetres or 1 metre 40 centimetres? Explain your answer.
  2. Convert 3 metres into centimetres.
  3. How many millimetres are there in 2 centimetres?
  4. Compare these two lengths: 900 millimetres and 0.9 metres. Which one is longer?
  5. Change 250 centimetres into metres.
  6. If a pencil is 18 centimetres long and a ruler is 30 centimetres long, how much longer is the ruler?
  7. Convert 4500 millimetres to metres.
  8. Which is shorter: 1.2 metres or 120 centimetres? Explain why.
  9. Write 2 metres 45 centimetres in centimetres only.
  10. Change 7 metres into millimetres.
  11. A piece of rope is 1 metre 75 centimetres long. Write this length in metres only (as a decimal).
  12. How many millimetres are in 5 metres?
  13. Order these lengths from shortest to longest: 3m, 250cm, 2800mm.
  14. Convert 620 centimetres into metres and centimetres.
  15. Which is longer: 1 metre 500 millimetres or 149 centimetres?
  16. If 1 metre = 100 centimetres, how many metres is 350 centimetres?
  17. A table is 120 centimetres long. Express this length in metres.
  18. How many millimetres are in 12 centimetres?
  19. Rewrite 2500 millimetres as metres and centimetres.
  20. Look at these lengths: 0.5 metres, 45 centimetres, and 600 millimetres. Arrange them from longest to shortest.

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Keep practising these types of questions to become confident at comparing and converting metric units of length! Remember to always check your units carefully and think about whether your answer makes sense. ✅

✔️ Answers to the Examination-Style Questions on Comparing and Converting Metric Units of Length

Here are the clear and simple answers to the 20 examination-style questions about comparing and converting metric units of length for Year 3 students. These answers will help you understand how to work with millimetres (mm), centimetres (cm), and metres (m).

  1. 150 cm is longer than 1 m 40 cm because 1 m 40 cm = 140 cm.
  2. 3 m = 300 cm.
  3. 2 cm = 20 mm.
  4. 900 mm = 0.9 m, so they are equal; neither is longer.
  5. 250 cm = 2.5 m.
  6. The ruler is 30 cm – 18 cm = 12 cm longer.
  7. 4500 mm = 4.5 m.
  8. 1.2 m = 120 cm, so they are equal; neither is shorter.
  9. 2 m 45 cm = 245 cm.
  10. 7 m = 7000 mm.
  11. 1 m 75 cm = 1.75 m.
  12. 5 m = 5000 mm.
  13. 2800 mm = 280 cm = 2.8 m; so order shortest to longest: 250 cm, 2800 mm, 3 m.
  14. 620 cm = 6 m 20 cm.
  15. 1 m 500 mm = 1 m 50 cm = 150 cm, which is longer than 149 cm.
  16. 350 cm = 3 m 50 cm.
  17. 120 cm = 1.2 m.
  18. 12 cm = 120 mm.
  19. 2500 mm = 2 m 50 cm.
  20. 0.5 m = 50 cm; 600 mm = 60 cm. So order: 600 mm (60 cm), 45 cm, 0.5 m (50 cm) → Longest to shortest is 600 mm, 0.5 m, 45 cm.

Remember, to convert between these metric units:

  • 1 metre (m) = 100 centimetres (cm)
  • 1 centimetre (cm) = 10 millimetres (mm)

Use these conversion facts to compare and change lengths easily! 👍