About this worksheet

This free Year 6 prime and composite numbers worksheet is written for the Western Australian curriculum and mapped to SCSA content description WA6MNAUN3. It focuses on one skill and is full of hands-on activities where children shade, draw, label and complete diagrams. By the end, students can say “I can use arrays and factors to decide whether a number is prime or composite, and explain why.”

What’s inside

• Key idea box – a short explanation with a worked, visual example to read before starting.
• A · Warm up (16 questions) – quick draw, shade and write practice to build confidence.
• B · Practise (9 questions) – worded problems in everyday Australian contexts, most with a diagram to work on.
• C · Think it through (5 questions) – explain your thinking: spot the mistake, true or false, always–sometimes–never, odd one out.
• D · Challenge (3 questions) – harder multi-step and problem-solving questions for students ready to stretch.
• Separate marking key – every answer with working, the correct shading and drawings shown in colour, and marking criteria for reasoning questions.

Skills covered

• Listing all the factors of a number
• Using arrays to decide if a number is prime or composite
• Finding the primes to 50 with a sieve

How to use this worksheet

Print the worksheet in black and white – all shading shows clearly in grey. Read the Key idea box together, then complete Section A. Most students should attempt Sections B and C; Section D suits students aiming high or preparing for extension and selective-entry maths. The worksheet is marked out of 57, and the score box on the last page shows which section needs more practice.

Common mistakes to watch for

• Thinking all odd numbers are prime, e.g. 9, 15 or 21
• Calling 1 a prime number
• Forgetting that 2 is prime because it is even
• Missing factor pairs, e.g. leaving 3 and 6 out of the factors of 18

Where this fits in the WA Year 6 sequence

Prime and Composite Numbers sits in the Understanding number sub-strand of Number and algebra. It is one of a set of short, single-skill EduLift worksheets that split each Year 6 content description into sub-skills. Use the previous and next links to work through the sequence in order.

Common errors we see in tutoring

• Thinking all odd numbers are prime, e.g. 9, 15 or 21
• Calling 1 a prime number
• Forgetting that 2 is prime because it is even
• Missing factor pairs, e.g. leaving 3 and 6 out of the factors of 18