Year 4 - Maths
Use knowledge of the distributive law to solve two part problems
Apply the distributive law to multiplication
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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 use knowledge of the distributive law to calculate products beyond known times tables facts and relate this to partitioning one of the factors.
Lesson Summary
You will learn to use knowledge of the distributive law to solve two part addition problems efficiently.
Key Notes
- Partitioning a factor is called distribution or using the distributive law.
- Factors can be re-combined to simplify 2-part addition problems.
- Five 9s plus three 9s is equal to eight 9s.
Vocabulary To Learn
- Common factors: When we compare lists of factors of two or more numbers, any factors that are the same are the common factors.
- Distributive law: The distributive law says that multiplying a number by a group of numbers added together is the same as doing each multiplication separately.
Common Mistakes To Avoid
- When looking at an expression such as 9 × 3 + 9 × 6 children might be tempted to add first leading to an expression like this: 9 × 12 × 6
3 Quick Questions (With Answers)
1. Solve this in steps: explain the method from this lesson and why each step matters.
Partitioning a factor is called distribution or using the distributive law. Factors can be re-combined to simplify 2-part addition problems.
2. Use this key word in a maths sentence and explain it clearly. 'Common factors'
When we compare lists of factors of two or more numbers, any factors that are the same are the common factors. Use this word when showing your method, then check your final answer is reasonable.
3. Spot and fix this common maths mistake.
Mistake: When looking at an expression such as 9 × 3 + 9 × 6 children might be tempted to add first leading to an expression like this: 9 × 12 × 6. Correction: Ensure that you support the equation with the arrays so that pupils understand where the multiplication expressions come from and they can match the partial products to the arrays.
More Lessons In This Unit
- Use knowledge of the distributive law to calculate products beyond known times tables Study Guide
- Use knowledge of the distributive law to calculate products using known times tables Study Guide
- Use knowledge of the distributive law to solve further two-part problems Study Guide
- Use knowledge of the distributive law to solve problems in different contexts Study Guide
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