Year 7

Prime Factorisation

Students learn about the fundamental theorem of arithmetic and explore the many properties of the prime factorisation of a number.

This is a classic reSolve sequence aligned with the Australian Curriculum V8.4. It is only available as a downloadable package.

This sequence of four lessons explores prime factorisation and how it can be used to solve problems related to the properties of numbers. The activities demonstrate why prime numbers are important. Proficiency goals are to reason mathematically about properties of numbers, and to carry out a mathematical investigation related to prime factorisation.

This sequence is for students who:

• have reasonable fluency with multiplication facts, although the sequence provides further practice.
• can use multiplication and division to find factors of a number.
• know the definition of prime and composite numbers and be able to give examples.

Lesson 1: Factor Strings

Students search a number grid for factor strings and then justify that the longest possible factor string for a number is made up of primes. This introduces the fundamental theorem of arithmetic: all whole numbers greater than 1 can be represented as a product of prime numbers in exactly one way.

Lesson 2: Prime Dice

Students play a game using dice labelled with prime numbers and learn how to use prime factorisations of a number to determine the properties of a number.

Lesson 3: Factors and Multiples

Students place numbers into a grid according to their properties. First, they do this with just the numbers, then they look at how prime factorisation can be used as an efficient way to determine number properties.

Lesson 4: HCF and LCM

This lesson explores how prime factorisation can efficiently determine the highest common factor (HCF) and lowest common multiple (LCM) of two numbers.

Last updated June 20 2020.

This is a classic reSolve sequence aligned with the Australian Curriculum V8.4. It is only available as a downloadable package.