Prime Numbers Introduction

Overview

Introduce Year 4 students to prime numbers using an engaging, hands-on grid activity that supports understanding through visual identification and colour-coding. This lesson aligns with the iE Curriculum for Maths, focusing on the properties of numbers and pattern recognition. Students will distinguish between prime and composite numbers by exploring a number grid and reflecting on multiplication factors.

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Curriculum Alignment

iE Curriculum Framework – Maths

• Number: Number and Place Value
  • Learning Objective: Identify, name and describe prime numbers up to 100.
  • Competency: Recognise patterns in numbers to determine prime and composite status.
• Number: Multiplication and Division
  • Learning Objective: Understand factors and use them to classify numbers as composite or prime.
  • Competency: Apply multiplication and division facts to support reasoning about number properties.

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Learning Objectives

By the end of this lesson, students will be able to:

• Define what a prime number is (a number greater than 1 with only two factors: 1 and itself).
• Identify prime numbers between 1 and 50 using a visual grid.
• Differentiate between prime and composite numbers through pattern recognition.
• Develop confidence in working collaboratively to discover mathematical properties.

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Materials Needed

• Large printed 10x10 number grids for pairs of students (numbers 1 to 100)
• Red and blue coloured pencils or markers
• Prime number checklist sheets
• Whiteboard and markers
• Sticky notes
• Mini whiteboards for quick formative assessment

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Lesson Structure

1. Starter Activity – Number Properties Warm-Up (5 minutes)

• Teacher writes a few numbers on the board (e.g., 5, 8, 11, 15).
• Ask students to identify which could be prime and which might not be, encouraging reasoning about factors they know (e.g., 5 is prime because only 1 and 5 divide it).
• Briefly introduce the definition of prime and composite numbers.

2. Introduction – Exploring the Grid (5 minutes)

• Show the 10x10 number grid to the class.
• Explain that they will colour code the numbers to find and mark prime and composite numbers visually.
• Outline the task:
  • Colour prime numbers red.
  • Colour composite numbers blue.
  • Leave 1 and 0 uncoloured (explain why 1 is neither prime nor composite).

3. Main Activity – Hands-On Grid Identification (25 minutes)

• Pair students and distribute grids and coloured pencils.
• Guide students through identifying prime numbers up to 50 first, with support from the teacher and peer discussion.
• Encourage use of known multiplication facts to check factors (e.g., 9 is composite because 3x3=9). Use mini whiteboards to jot down factor pairs if unsure.
• Circulate and ask probing questions: "Why did you colour that number red?" or "Can you find a factor of this number?"
• Allow students to extend colouring to 51-100 if confident, reinforcing prime identification up to 100.

4. Group Discussion – Pattern Recognition (10 minutes)

• Gather students and discuss observations:
  • Highlight prime number distribution on the grid — note that except 2 (the only even prime), primes are mostly odd.
  • Point out patterns, e.g., no primes beyond 2 are even numbers, many are located in seemingly random positions but follow specific rules regarding factors.
• Use sticky notes to let students write one interesting fact or pattern they noticed. Post around the room for a gallery walk.

5. Plenary – Formative Assessment (5 minutes)

• Quick quiz on mini whiteboards: Teacher calls out a number and students write “prime” or “composite.”
• Review answers collectively, reinforcing correct factor reasoning.
• Summarise the properties of prime numbers again.

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Differentiation

• Support: Provide a factor list sheet to help struggling students check number factors. Use smaller grids (1-50) for scaffolded practice.
• Extension: Challenge confident students to find twin primes within the grid or explore prime numbers beyond 100 as a homework task.

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Assessment Criteria

• Formative: Observations during grid activity, mini whiteboard quiz accuracy, participation in group discussion.
• Summative: Completed number grid colour coding correctly identifying prime and composite numbers; written sticky note reflections showing understanding of patterns.

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Reflection & Teacher Notes

• Emphasise visual and kinaesthetic learning through colouring and grid exploration.
• Reinforce that prime numbers form the foundation for many mathematical concepts, making this introduction crucial.
• Consider following lessons focusing on prime factorisation and using primes in problems solving.
• Collect grids as work evidence and provide personalised feedback highlighting students’ reasoning skills.

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This plan combines tactile learning with critical thinking to engage Year 4 students deeply with prime numbers while aligning strictly with the iE Curriculum requirements.