Year 5 - Maths
Use known facts and mental strategies to calculate with decimal numbers within and across a whole
Compose and calculate with decimals including column addition and subtraction
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Study Guides
This pupil-friendly study guide includes a unit summary, clear notes, common mistakes, and quick questions with answers.
Unit Summary
In this unit pupils will extend their understanding of formal calculation strategies to use column methods to add and subtract with decimal numbers.
Lesson Summary
You will learn to use known facts and mental strategies to calculate with decimal numbers within and across a whole.
Key Notes
- If you know that 5 + 2 is equal to 7 then 5 tenths + 2 tenths is equal to 7 tenths so 0.5 + 0.2 = 0.7
- Use known facts and unitising to add tenths.
- Bridging 10 strategies with whole numbers can be applied when the tenths bridge one whole.
Vocabulary To Learn
- Number facts: Simple calculations using two numbers are known as number facts. For example 2 + 4 = 6
- Bridging: Bridging is a mental strategy which uses addition or subtraction to cross a number boundary.
Common Mistakes To Avoid
- Pupils record missing part equations incorrectly.
3 Quick Questions (With Answers)
1. Solve this in steps: explain the method from this lesson and why each step matters.
If you know that 5 + 2 is equal to 7 then 5 tenths + 2 tenths is equal to 7 tenths so 0.5 + 0.2 = 0.7. Use known facts and unitising to add tenths.
2. Use this key word in a maths sentence and explain it clearly. 'Number facts'
Simple calculations using two numbers are known as number facts. For example 2 + 4 = 6. Use this word when showing your method, then check your final answer is reasonable.
3. Spot and fix this common maths mistake.
Mistake: Pupils record missing part equations incorrectly. Correction: Encourage children to match the equation to a representation identifying which number represents the wholes and which represent parts.
More Lessons In This Unit
- Explain that decimal numbers with tenths can be composed additively Study Guide
- Explain that decimal numbers with tenths can be composed multiplicatively Study Guide
- Use knowledge of column addition and subtraction to calculate with decimal numbers Study Guide
- Use representations to round a decimal number with tenths to the nearest whole number Study Guide
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