Use knowledge of the distributive law to solve further two-part problems
I can use knowledge of the distributive law to solve two part subtraction problems efficiently.
- Year 4
Use knowledge of the distributive law to solve further two-part problems
I can use knowledge of the distributive law to solve two part subtraction problems efficiently.
Lesson details
Key learning points
- 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.
Keywords
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 misconception
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
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.
Licence
Lesson video
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Prior knowledge starter quiz
6 Questions
Q1.Which of the numbers in the following equation is the product? 18 = 6 × 3
Q2.44 + 13 =
Q3.54 + 35 =
Q4.Which of the following expressions represents the total number of apples if I have 3 bags of 7 apples and 3 bags of 5 apples.
Q5.Which of the following expressions is the array representing?
Q6.Double 72 is ___
Assessment exit quiz
6 Questions
Q1.What is the common factor of the two multiplication expressions being added together in this equation? 6 × 5 − 4 × 5
Q2.Match the expressions that have equal value.
