Subtracting Tens Challenge

Learning Objectives

Aligned with the National Curriculum for England - Mathematics Key Stage 1, Number - Addition and Subtraction:

• MA1/1.3: "Recognise the place value of each digit in a two-digit number (tens, ones)"
• MA1/1.4: "Subtract one-digit and two-digit numbers to 20, including zero"
• MA1/1.5 (stretch): "Use mental methods to subtract a multiple of 10 from a two-digit number"

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WALT (We Are Learning To):

• Subtract 10 from two-digit numbers up to 200 using place value knowledge
• Develop mental subtraction strategies with tens
• Explain our thinking using mathematical vocabulary

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Success Criteria

• I can identify the tens and ones in a two-digit number
• I can subtract 10 from a two-digit number mentally
• I can show my subtraction using drawings, words or numbers
• I can explain how subtracting 10 affects the tens digit

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Lesson Outline (60 minutes)

1. Introduction and Recap (10 minutes)

• Brief whole-class discussion: What are tens and ones? Using a place value chart and place value counters or digit cards.
• Use concrete representations (e.g., sticks bundled in tens and single sticks) to visualise numbers up to 200.
• Quick warm-up: Identify the number of tens and ones in selected two-digit numbers (up to 200).
• Show a two-digit number like 74 on the board: "What is the tens digit? What is the ones digit?"

Teacher Talk: Explain that today we will be taking away 10 from numbers up to 200 and noticing what changes.

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2. Guided Practice: Subtracting 10 (15 minutes)

• Demonstrate subtracting 10 from several numbers using different representations:
  • Number line (jump back one group of ten)
  • Place value counters (remove one 'ten' stick)
  • Written subtraction (e.g., 74 - 10 = ?)
• Use the phrase: "Subtracting 10 means taking away one ten, so the tens digit decreases by 1, and the ones digit stays the same."
• Model this with numbers: 52 - 10 = 42, 110 - 10 = 100, 87 - 10 = 77.

Class Activity:
In pairs, children use place value counters or drawings to subtract 10 from given numbers up to 200, then share their answers and reasoning.

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3. Main Activity: Subtract 10 Challenge (20 minutes)

• Provide each child with a worksheet containing 15 subtraction questions subtracting 10 from two-digit and three-digit numbers (where the hundreds digit is 0 or 1, e.g., numbers up to 200). Examples: 120 - 10, 63 - 10, 99 - 10, 142 - 10.
• Children solve problems mentally first, then verify using drawings or number lines where needed.
• Encourage children to write a sentence explaining their answer for at least 3 problems: e.g., "When I take away 10 from 87, the tens go from 8 to 7, and the ones stay at 7."

Differentiation:

• Support: Use physical tens sticks and ones counters for hands-on subtraction, and work alongside teacher or teaching assistant.
• Scaffold: Provide a partially completed number line and sentence starters for explanation.
• Challenge: Include missing number questions: e.g., ___ - 10 = 130; or subtracting 20 from tough numbers to discuss how subtracting multiple tens works.

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4. Plenary: Reflection and Consolidation (10 minutes)

• Invite 4-5 students to share their explanation sentences aloud.
• Recap the pattern of subtracting 10: tens digit decreases by 1 and ones digit stays the same.
• Conduct a quick-fire number call: Teacher says a number, children mentally subtract 10 and hold up the answer on whiteboards.
• End with a pop quiz: Why does subtracting 10 not change the ones digit?

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5. Extension Activity (for early finishers or advanced learners)

• Introduce subtraction of multiples of 10, e.g., subtract 20, subtract 30 from two-digit numbers up to 200.
• Challenge: Solve word problems involving subtracting 10 from numbers beyond 100, e.g., "If I had 150 apples and gave away 10, how many do I have left?"

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Assessment

• Formative assessment through observation during paired activities and plenary discussions.
• Check subtraction worksheets for accuracy and explanations.
• Use quick-fire answers on whiteboards to assess mental subtraction fluency.
• Note which children can confidently explain their reasoning and those who need further support.

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Resources Needed

• Place value counters or sticks bundled in tens
• Number lines (large visual and individual mini number lines)
• Whiteboards and pens for quick responses
• Subtraction worksheets (designed with numbers up to 200 subtracting 10)
• Sentence starter cards for explanation support

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Differentiation Summary

Group	Strategies	Resources
SEN & Lower Ability	Use practical counters; work in small groups; sentence starters	Counters, concrete materials
Mainstream	Number lines and independent worksheet activity	Worksheets, number lines
Advanced	Introduce subtracting multiples of 10; missing number problems	Challenge problems in worksheet

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Notes for Teachers

• Emphasise consistent use of the sentence stem: “Subtracting 10 means...” to build mathematical language and reasoning.
• Regularly check understanding by asking pupils why the ones digit does not change.
• Use positive reinforcement when children independently use mental strategies.
• Incorporate physical movement by having children “jump back 10” on a floor number line for kinaesthetic learners.

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This highly focused lesson plan aligns precisely with the National Curriculum expectations for Year 1 pupils, ensuring engaging, hands-on learning that supports a deep understanding of subtracting 10 from numbers up to 200.