Number Operations · JHS3 Mathematics

Lesson notes

Learning Objectives

Indicator: B9.1.2.1.4 - Use the distributive property in solving problems.

By the end of the lesson, learners can:

State the distributive property in words and in symbols for both multiplication over addition and multiplication over subtraction.
Expand expressions of the form a × (b + c) and a × (b - c) using the distributive property.
Use the distributive property to compute products mentally, such as 6 × 47 and 8 × 99.
Combine the distributive property with the commutative and associative properties learned in Weeks 4 and 5 to simplify calculations.
Solve word problems by choosing when the distributive property makes the calculation easier than the standard method.

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Curriculum details

Strand: Number (Strand 1)
Sub-strand: Number Operations (1.2)
Content standard: B9.1.2.1 - Apply mental mathematics and properties to determine answers for addition and subtraction of basic facts.
Indicator: B9.1.2.1.4 - Use the distributive property in solving problems.
Suggested placement: Term 1, Week 5 (Week 5 of the year)
Our suggestion, laid out in curriculum order across three terms of twelve weeks. NaCCA does not fix the week, so follow your school's scheme of learning.
Curriculum reference: Mathematics, Common Core Programme (JHS1-JHS3), 2023, p. 169
Transcribed from the official NaCCA publication. Check this page against the source.

Exemplars (from the NaCCA curriculum)

E.g1. Recognise that for any three numbers a, b and c;
i. a × (b + c) = (a × b) + (a × c) i.e. 5 × (10 + 7) = (5 × 10) + (5 × 7) = 85
ii. a × (b - c) = (a × b) - (a × c) i.e. 5 × (10 - 7) = (5 × 10) - (5 × 7) = 15