B5 Mathematics · Term 1 Week 5: Counting, Representation & Cardinality

Lesson notes

Learning Objectives

Indicator: B5.1.1.3.2 - Generate and identify prime numbers and composite numbers between 1 and 100

By the end of the lesson, learners can:

Define prime numbers as numbers with exactly two factors (1 and the number itself) and composite numbers as numbers with more than two factors.
Use arrays or the factorization method to determine all factors of numbers from 1 to 30.
Apply the Sieve of Eratosthenes to identify all prime numbers between 1 and 100.
Classify numbers from 1 to 100 as prime, composite, or neither (1).
Justify why a given number is prime or composite by listing its factors.

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Curriculum details

Strand: Number (Strand 1)
Sub-strand: Counting, Representation & Cardinality (1.1)
Content standard: B5.1.1.3 - Demonstrate an understanding of factors, multiples of numbers including composite, even, odd and prime numbers from 1 to 100
Indicator: B5.1.1.3.2 - Generate and identify prime numbers and composite numbers between 1 and 100
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.
Source document note: The official curriculum document has a fault in this entry, so the curriculum text above is transcribed exactly as printed:

exemplars - p.61
Curriculum reference: Mathematics Curriculum for Primary Schools (Basic 4-6), 2019, p. 61
Transcribed from the official NaCCA publication. Check this page against the source.

Exemplars (from the NaCCA curriculum)

E.g. 1 Ask learners to use different arrangements of arrays of objects (or the factorization method) to find factors of the first 30 whole numbers and use their results to complete the table below. Have learners identify prime numbers; i.e. number with only two factors, 1 and the number itself; other are composite.

Figure from the b5 mathematics curriculum, printed page 61

E.g. 2 In convenient groups, have learners use the "Sieve of Eratosthenes" to identify prime numbers between 1 and 100, i.e. dividing through by whole numbers starting from 2; numbers that cannot be divided by other numbers except the number itself are prime numbers.

 The Numbers / Factors / Number of factors table is set below E.g. 1 and its cells interleave with the exemplar in the text layer; the figure shows it.