How to Teach Doubling and Halving in KS1 & KS2
Understanding doubling and halving is essential to building solid number sense in primary school pupils. These foundational skills are not just part of early mental maths—they are building blocks for multiplication, division, fractions, and problem-solving strategies used throughout KS1 and KS2. Effective teaching of these concepts requires more than worksheets; it involves clear modelling, structured progression, and regular, real-life applications.
What Are Doubling and Halving?
Doubling is the process of adding a number to itself. For example, doubling 4 gives 8. Halving is the inverse—splitting a number into two equal parts. For example, half of 8 is 4. These concepts should be introduced early, using concrete resources and visual representation before moving on to mental methods and abstract problems.
In the National Curriculum, children are expected to double and halve numbers mentally by the end of Year 2 and apply these skills confidently through KS2 in larger number contexts and word problems.
Step-by-Step Progression for KS1
1. Begin with Practical Resources
Young learners in Reception and Year 1 benefit greatly from seeing doubling and halving physically. Use counters, cubes, dominoes, or even snack items to demonstrate these operations. Double 2 buttons on one hand to make 4. Halve 10 grapes between two plates.
2. Connect to Real-Life Contexts
In KS1, real-life stories help build relevance. Halving a sandwich, doubling the number of eyes on a teddy bear, or sharing pencils between two friends makes maths meaningful.
3. Introduce Doubling and Halving Vocabulary
Use clear and consistent language: double, halve, share equally, twice as many. Reinforce vocabulary through classroom posters and oral games.
4. Use Visual Representations
Number lines, ten frames, and part-part-whole models help children visualise the process. Show how double 5 jumps to 10 on a number line. Use a part-whole diagram to split 8 into two equal parts of 4.
5. Encourage Mental Strategies
Once children are confident with concrete examples, guide them towards mental recall of key doubles and halves. Encourage them to use known facts (double 5 = 10) to solve more complex ones (double 6 = double 5 + 2).
Teaching Doubling and Halving in KS2
By KS2, children should have secure knowledge of doubling and halving facts up to 20 and begin applying these to larger numbers and decimals.
1. Build on Prior Knowledge
Start by revising doubles and halves up to 20. Then move into doubling multiples of 10, 100, and using partitioning strategies.
Example:
Double 36 = Double 30 + Double 6 = 60 + 12 = 72
Half of 84 = Half of 80 + Half of 4 = 40 + 2 = 42
2. Integrate with Multiplication and Division
Help pupils see the connection between doubling and multiplication by 2, and halving with division by 2. Link to the 2, 4, and 8 times tables.
Example:
If 2 × 12 = 24, then half of 24 = 12
If 4 × 6 = 24, then double 12 = 24
3. Apply to Word Problems
Use doubling and halving in context. Problems involving quantities, money, measurement, and area can all embed these skills. Encourage estimation and mental strategies as part of the solution.
4. Introduce Doubling with Decimals
In upper KS2, include decimals in practice.
Double 0.6 = 1.2
Half of 1.8 = 0.9
Use place value charts and bar models to show how this works visually.
Strategies to Reinforce Learning
Use Doubling and Halving Games
Interactive tools like Hit the Button’s “Doubling and Halving” game allow children to practise quick recall in a fun, competitive setting. The game adjusts difficulty and is ideal for both KS1 and KS2 learners.
Flashcard Drills and Partner Games
Use flashcards for quick recall drills. Children can quiz each other in pairs: “What’s double 7?” “What’s half of 16?” This encourages active learning and peer feedback.
Maths Journals and Reasoning Questions
Ask children to explain their thinking:
“Explain how you halved 56.”
“What patterns do you notice when doubling even numbers?”
Use Regular Starters and Warm-Ups
Start the maths lesson with a quick round of doubling or halving questions. Use whiteboards or mental maths races to energise pupils and embed these facts through repetition.
Common Misconceptions
- Thinking halving is subtracting 1: Clarify that halving means dividing into two equal parts, not just making the number smaller.
- Confusing doubling with adding 2: Reinforce the meaning of ‘twice as much’ with visual support.
- Difficulty with odd numbers: Use manipulatives and number lines to show that halves of odd numbers can result in fractions (e.g. half of 7 = 3.5).
Supporting Learners Who Struggle
- Go back to concrete examples: Use items they can touch and count.
- Break it down: Use scaffolding like part-part-whole or ten frames.
- Practise in short bursts daily: Repetition builds confidence.
- Use rhythm and chant: “Double 2 is 4, double 3 is 6…”
Extending High Achievers
- Introduce doubling and halving in patterns: Explore sequences like 1, 2, 4, 8, 16…
- Create their own doubling and halving games or puzzles.
- Apply skills to solve logic-based problems or multi-step word problems.
Conclusion
Doubling and halving may seem simple on the surface, but they lay the groundwork for powerful number strategies throughout primary school. By carefully introducing these concepts using concrete tools, visual models, and contextual problems, teachers can ensure learners don’t just memorise but understand the reasoning behind the operations.
With regular practice, games like Hit the Button, and meaningful classroom conversations, children can master doubling and halving as mental maths essentials—and enjoy doing it along the way.