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Year 3 - Maths

Count across and on from 100

Bridging 100: counting on and back in 10s, adding/subtracting multiples of 10

Unit Summary

In this unit pupils will find pairs of number that compose 100. They will position 3-digit numbers on a number line and estimate their position on unmarked number lines. They will compare and order 3-digit numbers.

Lesson Summary

You will learn to count up to, on from and across one hundred.

Key Notes

  • Knowledge of place value can help when counting forwards across the 100 boundary.
  • Knowledge of place value can help when counting backwards across the 100 boundary.
  • Knowing the pattern of counting in 10s can help us when counting forwards and backwards across the 100 boundary.

Vocabulary To Learn

  • 100s boundary: The point at which the numbers change into 100s numbers or from one set of hundreds to another.
  • Pattern: When objects or numbers are arranged following a rule. A pattern is a repeated set of numbers, shapes or objects.

Common Mistakes To Avoid

  • Pupils may struggle crossing over the hundreds boundary (99 to 100, and back from 100 to 99).

3 Quick Questions (With Answers)

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

Knowledge of place value can help when counting forwards across the 100 boundary. Knowledge of place value can help when counting backwards across the 100 boundary.

2. Use this key word in a maths sentence and explain it clearly. '100s boundary'

The point at which the numbers change into 100s numbers or from one set of hundreds to another. Use this word when showing your method, then check your final answer is reasonable.

3. Spot and fix this common maths mistake.

Mistake: Pupils may struggle crossing over the hundreds boundary (99 to 100, and back from 100 to 99). Correction: It may help pupils to understand that 100 is ten lots of ten. This is the lesson focus and pupils will have lots of practise opportunities.

More Lessons In This Unit

Browse all guides in the Year 3 Maths guide library.