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Year 1 - Maths

Finding the missing number from 0 to 20

Counting to and from 20

Unit Summary

In this unit pupils will consolidate counting to 20 and back They will secure their understanding of the teens numbers in a cardinal and an ordinal context.

Lesson Summary

You can find the missing number from 0 to 20.

Key Notes

  • Use knowledge of stable order principle to figure out missing numbers on a number track.
  • Use knowledge of one more than and one less than to work out missing numbers in number tracks.

Vocabulary To Learn

  • one more: The next number in the count is one more than the number before and there will be one more object in the set.
  • one less: The previous number in the count is one less than the next number and there will be one fewer object in the set.

Common Mistakes To Avoid

  • Not being secure with the order of the numbers from 11 to 20 when not starting at 0 or 1.

3 Quick Questions (With Answers)

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

Use knowledge of stable order principle to figure out missing numbers on a number track. Use knowledge of one more than and one less than to work out missing numbers in number tracks.

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

The next number in the count is one more than the number before and there will be one more object in the set. Use this word when showing your method, then check your final answer is reasonable.

3. Spot and fix this common maths mistake.

Mistake: Not being secure with the order of the numbers from 11 to 20 when not starting at 0 or 1. Correction: Practice counting starting from different points within 11 to 20 and model the first 3 to establish a pattern.

More Lessons In This Unit

Browse all guides in the Year 1 Maths guide library.