About this worksheet

Understanding the difference between prime and composite numbers is a key building block for Year 4 students’ number sense, linking directly to their work on factors and factor pairs. This worksheet gives students focused practice classifying numbers based on how many factors they have.

The worksheet follows EduLift’s four-part structure, with 29 questions worth 53 marks in total. The Fluency section (16 marks) has students classify numbers from 2 to 25 as prime or composite. The Core section (21 marks) extends this to listing primes and composites within a range and reasoning about specific numbers such as 9, 29 and 51. The Reasoning section (9 marks) asks students to explain the difference between prime and composite numbers, justify why 1 is neither, and correct a common misconception about odd and even primes. The Challenge section (7 marks) extends students with prime-number puzzles, including a simplified Goldbach-style problem.

Every question and answer on this worksheet has been checked for accuracy, and the worksheet has been reviewed for clear layout and age-appropriate language before publishing.

This worksheet is aligned to the WA SCSA Mathematics curriculum for Year 4, under the Number and Algebra strand (code WA4MNAFA1), and is free to download and use for classroom or home practice.

Common errors we see in tutoring

• Assuming all odd numbers are prime
• Assuming all prime numbers are odd (forgetting 2)
• Classifying 1 as prime instead of recognising it as neither
• Not checking all possible factors before concluding a number is prime