Year 2 - Maths
Calculate the difference in different contexts
Calculating within 20
Study Hub
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 add 3 addends. They will use a strategy such as finding 2 addends to total 10 or 2 numbers to bridge though 10.
Lesson Summary
You will learn to calculate the difference in different contexts.
Key Notes
- You calculate the difference by counting on from the known part to the whole.
- The difference is the answer to a subtraction calculation.
- The difference is one of the parts that make the whole.
Vocabulary To Learn
- Difference: The amount which a number is greater or smaller.
- Subtraction: To partition one part from another (the subtrahend from the difference), or to decrease an amount by taking an amount away.
- Count on: A mental strategy used to add numbers.
Common Mistakes To Avoid
- Children think that 'counting on' is used solely as a strategy in addition.
3 Quick Questions (With Answers)
1. Solve this in steps: explain the method from this lesson and why each step matters.
You calculate the difference by counting on from the known part to the whole. The difference is the answer to a subtraction calculation.
2. Use this key word in a maths sentence and explain it clearly. 'Difference'
The amount which a number is greater or smaller. Use this word when showing your method, then check your final answer is reasonable.
3. Spot and fix this common maths mistake.
Mistake: Children think that 'counting on' is used solely as a strategy in addition. Correction: Children should be made aware that the strategy for 'counting on' can be used in addition but is used as a strategy for subtraction in this lesson where we are finding the difference between two numbers close in value.
More Lessons In This Unit
- Add and subtract two numbers that bridge through 10 Study Guide
- Add three addends Study Guide
- Add three addends efficiently Study Guide
- Add three addends efficiently by finding two addends that total 10 Study Guide
- Add two numbers that bridge through 10 Study Guide
- Calculate the difference Study Guide
- Calculate the difference when information is presented in a bar chart Study Guide
- Calculate the difference when information is presented in a pictogram Study Guide
- Compare the number of objects in two sets or difference between two measures. Study Guide
- Explain that the addends can be added in any order Study Guide
- Explain what the difference is between consecutive numbers Study Guide
- Use a 'First, then, then, now' story to add three addends Study Guide
- Use knowledge of calculating within 20 to solve problems Study Guide
- Use knowledge of calculating within 20 to solve problems involving statistics Study Guide
Browse all guides in the Year 2 Maths guide library.