Making Twenty Fun

Overview

Duration: 35 minutes
Key Stage: KS2 – Year 3
Curriculum Area: Mathematics – Number: Addition & Subtraction
Focus Topic: Ways to Make 20
Group Size: 1 pupil
Observation Context: Vice Principal Observation – focus on GTCNI Competencies and behaviour management

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Learning Intentions

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

• Recognise and represent multiple addition and subtraction number sentences that total 20.
• Identify inverse operations: linking addition and subtraction facts.
• Demonstrate an understanding of number bonds to 20 through visual and written representations.
• Use manipulatives (e.g. cubes, number lines, hundred square) appropriately to support their calculations.
• Reflect good learning behaviour: attention, engagement and perseverance in independent work.

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Success Criteria

The pupil will:

• Accurately count representations using dots to calculate number bonds to 20.
• Write all matching number sentences (e.g., 16 + 4, 4 + 16, 20 − 16, 20 − 4).
• Use strategies and resources such as number lines, hundred squares, and cubes independently when needed.
• Show a focused, positive learning attitude throughout the activity.
• Participate actively during teacher modelling and the plenary game.

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GTCNI Competencies Addressed

• Competency 1: Professional Values and Practice – Promotes positive behaviour and high expectations.
• Competency 2: Professional Knowledge and Understanding – Demonstrates deep knowledge of how to teach Mathematics in line with the NI Curriculum.
• Competency 3: Professional Skills and Application – Plans effectively, uses appropriate resources, and employs a range of teaching strategies.

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Resources

• Whiteboard and pens
• Pre-prepared dot representation worksheet focused on "Ways to Make 20"
• Number lines, hundred square (for reference)
• Multilink cubes (support for lower ability)
• Pupil pencil and workbook
• iPad/laptop with “Hit the Button” preloaded (only for early finishers)

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Lesson Structure

1. Settling and Starter (5 mins)

• Routine Reinforcement: Greet pupil at door, settled on the carpet with whiteboard and pen ready.
• Behavioural Expectation Reminder: “Today we are showing the Vice Principal how amazing our learning behaviours are. Eyes on me, quiet hands, and ready minds.”
• Review Prior Knowledge: “Last week we explored ways to make 10 and 15. Can anyone remember one way?”
• Model 2 examples of ways to make 10 using dot cards on whiteboard. Elicit from pupil how the dots link to number sentences.

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2. Teacher Modelling on Whiteboard (7 mins – on the mat)

• Display Image: Dot representation totalling 20.
• Think Aloud: “Let’s count the red dots – 16. Now the blue dots – 4. Altogether that’s 20.”
• Write it as: 16 + 4 = 20, then flip the addition: 4 + 16 = 20
• Guide pupil to discover the subtractions:
  “If I have 20 and take away 4, how many are left?”
  Write: 20 − 4 = 16, then 20 − 16 = 4
• Highlight that one diagram links four number facts.
• Invite pupil to try next example on their whiteboard with support.

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3. Pupil Independent Activity (15 mins – at own desk)

Worksheet Activity

• Pupil completes a themed worksheet (differentiated and familiar template) focused on dot representations that total 20.
• For each image:
  • Count dots and write the two addition and two subtraction sentences.
  • Reinforce the use of inverse relationships.

Targeted Support

• Provide number line/hundred square for guidance.
• Offer multi-link cubes as needed to support counting or bridging understanding.
• Encourage verbalising steps before writing (self-talk strategy).

Behaviour Management Strategy

• Use named praise (“This is star learner behaviour”) and timer (if needed) for focus.
• Offer ‘brain break’ sticker after every completed page.

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4. Extension (3 mins – Ongoing for early finishers)

Interactive Game: Hit the Button

• Use iPad or laptop
• Focus: Number bonds to 20 (addition & subtraction)
• Encourage pupil to beat their own score and record it.

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5. Plenary and Reflection (5 mins – back to the mat)

• Share one completed worksheet together, read the four number sentences aloud.
• Recap how one image can make four number sentences.
• Ask prompting questions:
  • “What patterns did you notice in the numbers?”
  • “Which tool helped you most today – the cubes, the number line or your brain?”
• Emphasise achievement using Learning Powers (e.g., Resilience, Problem-Solving).

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Assessment for Learning (AfL)

• During lesson:
  • Use questioning to guide understanding during modelling and independent task.
  • Observe use of manipulatives and whiteboard during scaffolded tasks.
• Post-lesson checks:
  • Review worksheet for accuracy and completeness.
  • Log notes on pupil strengths, misconceptions, and confidence.
  • Plan follow-up based on whether pupil transfers understanding to new number targets.

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Differentiation & Inclusion

• Support: Multi-link cubes and teacher guidance when counting. Encourage touch-and-count method.
• Challenge: Ask pupil to predict a missing addend for a sentence: “20 − ? = 11”, or write a word problem based on a number sentence.

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Cross-Curricular Opportunities

• Literacy: Use of full sentences to explain number relationships aloud.
• ICT: Digital fluency through approved interactive maths game.

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Teacher Reflection Prompt

• Did the pupil independently connect the inverse operations?
• Was the pupil able to explain their thinking clearly?
• How did on-task behaviour influence the pace and quality of learning?

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Key Vocabulary

• Add, subtract, equals
• Total, altogether
• Inverse, number sentence
• Number bond, dot pattern

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Follow-Up & Homework Suggestion

• Continued practice with “Ways to Make X” extending beyond 20.
• Home challenge sheet with creative prompts:
  “Draw your own dots that make 20 and challenge a grown-up to write all four number sentences.”

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Final Notes for Observation

• Clear progression from modelling to independent application.
• Familiar format allows pupil confidence to grow.
• Focused, inclusive teaching with behaviour and positivity central to learning environment.

📌 Observation Tip: Have learning objective and success criteria clearly displayed. Keep behaviour-specific praise frequent and linked to learning (“That’s great perseverance – you used the cubes really well to solve that one!”).

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✨ This is a concise but rich lesson that blends visual, numerical, and kinaesthetic learning styles – age-appropriate and curriculum-aligned.