Explain how to identify a prime factor of a number
Lesson details
Learning outcome
I can explain how to identify a prime factor of a number.
Key learning points
- All numbers can be written as a product of 2 or more prime numbers.
- A prime factor is a factor of a number which is prime.
Keywords
Factor - A factor is a whole number which exactly divides another whole number.
Prime factor - A prime factor is a factor of a number that is a prime number.
Common misconception
Pupils try to compose numbers additively using prime factors.
Ensure pupils are confident with finding the factors of a number first before extending to finding prime factors of known factors. Give time to building numbers with prime factors in arrays to help emphasise their multiplicative composition.
Teacher tip
You might like to explore how prime factors are applied in the making and breaking of secret codes based on numbers. This is known as 'encryption' or 'cryptography'.
Licence
Lesson video
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Prior knowledge starter quiz
6 Questions
Q1.Match the number to the correct type.
Q2.True or false: 19 is a prime number.
Q3.Tick the prime numbers.
Q4.Complete: 4 × 2 × 3 =
Q5.What square number is represented by this incomplete factor bug?
Q6.Match the expression to the correct product.
Assessment exit quiz
6 Questions
Q1.True or false: 25 is a prime number.
Q2.Tick the prime numbers.
Q3.What are the prime factors shown in this factor bug?
Q4.The factor bug shows the factors of 16 Which of the calculations below correctly shows 16 decomposed into prime factors?
Q5.The factor bug shows the factors of 30 Which of the calculations below correctly shows 30 decomposed into prime factors?
Q6.What is the missing prime factor? 51 = 3 ×
To help you plan your 5 maths lesson on: Explain how to identify a prime factor of a number, download all teaching resources for free and adapt to suit your pupils' needs...
To help you plan your 5 maths lesson on: Explain how to identify a prime factor of a number, download all teaching resources for free and adapt to suit your pupils' needs.
The starter quiz will activate and check your pupils' prior knowledge, with versions available both with and without answers in PDF format.
We use learning cycles to break down learning into key concepts or ideas linked to the learning outcome. Each learning cycle features explanations with checks for understanding and practice tasks with feedback. All of this is found in our slide decks, ready for you to download and edit. The practice tasks are also available as printable worksheets and some lessons have additional materials with extra material you might need for teaching the lesson.
The assessment exit quiz will test your pupils' understanding of the key learning points.
Our video is a tool for planning, showing how other teachers might teach the lesson, offering helpful tips, modelled explanations and inspiration for your own delivery in the classroom. Plus, you can set it as homework or revision for pupils and keep their learning on track by sharing an online pupil version of this lesson.
Explore more key stage 2 maths lessons from the Understand and use the concept of factorisation (square and prime numbers) unit, dive into the full primary maths curriculum, or learn more about lesson planning.