Adding Across 10s

Overview

A 30-minute lesson designed for Year 3 students to develop fluency and confidence in adding single-digit numbers across multiples of ten (e.g., 29 + 4, 47 + 6), directly aligned with the National Curriculum for England Key Stage 2 Maths standards.

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National Curriculum Links

Mathematics Programmes of Study – Year 3:

• Number – Addition and Subtraction
  • Add and subtract numbers mentally, including: a three-digit number and ones.
• Number – Number and Place Value
  • Recognise the place value of each digit in a three-digit number (hundreds, tens, and ones).

Learning Objectives

• LO1: Pupils will mentally add a single-digit number to a two-digit number that crosses a multiple of ten.
• LO2: Pupils will explain their mental strategy using place value knowledge (partitioning into tens and ones).
• LO3: Pupils will demonstrate confidence in recognising and using ‘bridge ten’ techniques to simplify addition.

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Resources

• Whiteboard and markers
• Individual mini-whiteboards and pens (for all pupils)
• Number cards (0-9), large to share with class
• Counters or place value blocks (optional, for visual demonstration)
• “Bridge 10” visual poster that illustrates tens crossing (prepared before class)
• Printed activity sheets with varied questions

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Lesson Structure

Introduction (5 minutes)

1. Engage: Start with a quick mental warm-up - ask pupils to add 1, 2, or 3 to a given number under 10 (e.g., 7 + 2).
2. Hook: Use the poster to introduce adding across tens - for example: adding 1 to 29 to make 30, then adding the rest. Explain “bridging ten.”
3. Model: Using a number card (29) and a single-digit number card (4), demonstrate step-by-step how to add by partitioning the 4 into 1 + 3 to cross the ten.

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Main Activity (20 minutes)

Activity 1: Guided Practice (10 minutes)

• Write several examples on the board (e.g., 37 + 5, 48 + 4).
• Ask pupils to work out the answer using mini-whiteboards, encouraging them to verbalise the steps aloud:
  • Partition the small number to reach the next multiple of 10.
  • Add to the nearest ten first.
  • Add the leftover units.
• Use place value blocks or counters for visual support if needed.

Activity 2: Independent Application (10 minutes)

• Pupils complete an activity sheet with varied questions: adding 1s, 2s, and up to 6s across tens (e.g., 56 + 3, 29 + 6).
• Circulate to check understanding; prompt students explaining their thinking in terms of tens and ones.

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Plenary (5 minutes)

• Select 3-4 pupils to explain their mental addition strategy for a question from the activity sheet, reinforcing use of bridging ten.
• Ask the class: “Why is knowing about tens and ones helpful when adding?”
• Summarise the learning – emphasise that recognising place value helps “break down” tricky additions into easier steps.

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Assessment and Feedback

• Formative assessment through observation during guided work and plenary explanations.
• Quick check of activity sheets to confirm correct application of bridging ten method.
• Use mini-whiteboards responses to identify pupils who may need further support.

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Differentiation

• Support: Provide counters or place value charts for pupils who struggle with mental strategies.
• Challenge: Offer extended problems involving adding across multiples of 100 with similar bridging strategies (e.g., 198 + 7).
• Encourage more able pupils to explain alternative strategies or use larger numbers.

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Cross-Curricular Links

• English: Encourage clear oral explanations to improve mathematical communication skills.
• PSHE: Foster growth mindset by highlighting that mental strategies improve with practise, reinforcing confidence.

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Additional Ideas to Wow

• Incorporate a short “Maths Magic Trick”: use mental addition to quickly “guess” a total before revealing the steps. For example, show pupils that when adding numbers crossing a ten, breaking it down makes the problem simpler and faster.
• Use an interactive “tens bridge” game on the whiteboard where pupils drag units to complete the next multiple of ten and solve the sum collaboratively.
• End lesson with a quick “Number Talk” reflecting on what mental strategies were easiest or trickiest.

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This lesson plan ensures that Year 3 learners develop solid mental addition skills aligned precisely with the National Curriculum's emphasis on place value understanding and mental arithmetic fluency.