Number Operations · B4 Mathematics

Lesson notes

Learning Objectives

Indicator: B4.1.2.2.1 - Apply mental mathematics strategies and number properties, such as skip counting from a known fact using doubling or halving using patterns in the 9s facts using repeated doubling or halving to determine answers for basic multiplication facts to 81 and related division facts

By the end of the lesson, learners can:

Use skip counting up or down from a known fact to find a related multiplication fact (e.g., use 5 × 7 = 35 to find 6 × 7 and 4 × 7).
Apply the doubling strategy to find multiplication facts (e.g., use 4 × 3 = 12 to find 8 × 3 = 24).
Use the pattern for multiplying by 9 (subtract the number from 10 times the number) to find products up to 81.
Use repeated doubling or repeated halving to solve multiplication and division facts (e.g., 60 ÷ 4 = 15).
Relate division facts to known multiplication facts (e.g., for 64 ÷ 8, think 8 × 8 = 64).

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Curriculum details

Strand: Number (Strand 1)
Sub-strand: Number Operations (1.2)
Content standard: B4.1.2.2 - Describe and apply mental mathematics strategies and number properties to determine answers for basic multiplication facts to 81 and related division facts
Indicator: B4.1.2.2.1 - Apply mental mathematics strategies and number properties, such as skip counting from a known fact using doubling or halving using patterns in the 9s facts using repeated doubling or halving to determine answers for basic multiplication facts to 81 and related division facts
Suggested placement: Term 1, Week 9 (Week 9 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 Curriculum for Primary Schools (Basic 4-6), 2019, p. 15
Transcribed from the official NaCCA publication. Check this page against the source.

Exemplars (from the NaCCA curriculum)

E.g. 1 Describe the mental mathematics strategies used to determine a given basic fact, such as
- skip count up by one or two groups from a known fact (e.g., if 5 × 7 = 35, then 6 × 7 is equal to 35 + 7 and 7 × 7 is equal to 35 + 7 + 7)
- skip count down by one or two groups from a known fact (e.g., if 8 × 8 = 64, then 7 × 8 is equal to 64 - 8 and 6 × 8 is equal to 64 - 8 - 8)
- doubling (e.g., for 8 × 3 think 4 × 3 = 12, and 8 × 3 = 12 + 12)
- patterns when multiplying by 9 (e.g., for 9 × 6, think 10 × 6 = 60, and 60 - 6 = 54; for 7 × 9, think 7 × 10 = 70, and 70 - 7 = 63)
- repeated doubling (e.g., if 2 × 6 is equal to 12, then 4 × 6 is equal to 24 and 8 × 6 is equal to 48)
- repeated halving (e.g., for 60 ÷ 4, think 60 ÷ 2 = 30 and 30 ÷ 2 = 15)
- relating division to multiplication (e.g., for 64 ÷ 8, think 8 × … = 64)
E.g. 2 Recall multiplication facts to 81 and related division facts