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Year 3 - Maths

Millimetres as a unit of measure and the relationship between them and cm

Measuring length and recording in tables

Unit Summary

In this unit pupils will continue to measure using appropriate tools and units progressing to using a wider range of measures, including comparing and using mixed units.

Lesson Summary

You will learn to understand millimetres as a unit of measure and describe the relationship between mm and cm.

Key Notes

  • Small objects are measured in millimetres.
  • There are 10 mm in 1 cm

Vocabulary To Learn

  • millimetre: A millimetre is a standardised unit of measurement. We can abbreviate millimetre to mm.

Common Mistakes To Avoid

  • Children may think that 10 mm are larger than 1 cm.

3 Quick Questions (With Answers)

1. Solve this in steps: explain the method from this lesson and why each step matters.

Small objects are measured in millimetres. There are 10 mm in 1 cm.

2. Use this key word in a maths sentence and explain it clearly. 'millimetre'

A millimetre is a standardised unit of measurement. We can abbreviate millimetre to mm. Use this word when showing your method, then check your final answer is reasonable.

3. Spot and fix this common maths mistake.

Mistake: Children may think that 10 mm are larger than 1 cm. Correction: There are 10 mm in 1 cm. 1 cm is made up of 10 mm. 10 mm and 1 cm are equivalent in length.

More Lessons In This Unit

Browse all guides in the Year 3 Maths guide library.