Year 4 - Maths
Use knowledge of the distributive law to solve further 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 subtraction problems efficiently.
Key Notes
- Partitioning a factor is called distribution or using the distributive law.
- Partitioned factors can be subtracted to simplify two-part subtraction problems.
- Eight 9s subtract three 9s is equal to five 9s.
Vocabulary To Learn
- Common factor: 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 5 × 6 − 5 × 3 children might be tempted to subtract first leading to an expression like this: 5 × 1 × 3
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. Partitioned factors can be subtracted to simplify two-part subtraction problems.
2. Use this key word in a maths sentence and explain it clearly. 'Common factor'
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 5 × 6 − 5 × 3 children might be tempted to subtract first leading to an expression like this: 5 × 1 × 3. 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 problems in different contexts Study Guide
- Use knowledge of the distributive law to solve two part problems Study Guide
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