Year 2 - Maths
Use knowledge of calculating within 20 to solve problems involving statistics
Calculating within 20
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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 use knowledge of calculating within 20 to solve problems involving statistics.
Key Notes
- When adding three addends, it is efficient to first add two addends using a known fact e.g. pair to 10 or double.
- When adding, we can bridge 10 by partitioning a part so that we can 'make 10'.
- When subtracting, we can bridge 10 by partitioning a part to create a part that is equal to the ones digit of whole.
- The difference can be found through subtraction.
Vocabulary To Learn
- Interpret: Understand and give meaning to mathematical data.
- Efficient: Not wasting time or effort. An efficient strategy is one we can carry out easily.
- Bridge 10: Addition or subtraction that crosses the 10 boundary.
- Difference: The result of subtracting one number from another. Way in which two or more things we are comparing are not the same.
Common Mistakes To Avoid
- Children may struggle to correctly read the information presented within the pictogram/bar chart.
3 Quick Questions (With Answers)
1. Solve this in steps: explain the method from this lesson and why each step matters.
When adding three addends, it is efficient to first add two addends using a known fact e.g. pair to 10 or double. When adding, we can bridge 10 by partitioning a part so that we can 'make 10'.
2. Use this key word in a maths sentence and explain it clearly. 'Interpret'
Understand and give meaning to mathematical data. 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 struggle to correctly read the information presented within the pictogram/bar chart. Correction: A ruler can be used to help children line up the top of the bar with the scale. Model this as a strategy to support accurate reading.
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 in different contexts 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
Browse all guides in the Year 2 Maths guide library.