Number Bonds to 20 Worksheets — KS1
Number bonds are the building blocks of mental arithmetic. Secure knowledge of all pairs that total 10 and 20 allows children to calculate quickly and confidently without counting. The UK National Curriculum expects Year 1 children to know number bonds to 10 and Year 2 children to know bonds within 20. Our worksheets provide the varied, repeated practice needed to move from counting strategies to instant recall.
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Key Skills Covered
From Bonds to 10 to Bonds to 20
Children first develop secure knowledge of bonds to 10 (1+9, 2+8, 3+7…) before extending to 20. Understanding that bonds to 10 can be doubled (since 10 is half of 20) is a key stepping stone. For example, knowing 6+4=10 helps children work out 16+4=20. Our worksheets build this connection explicitly, helping children use what they already know rather than learning entirely new facts.
Teaching Representations
Our number bonds to 20 worksheets use multiple representations including ten frames (showing how numbers are composed of tens), part-whole models (with one part missing), number lines, and simple addition equations. Research on maths mastery (following Singapore and Shanghai models) shows that moving through concrete, pictorial, and abstract representations develops deeper understanding than abstract practice alone.
Sample Questions
13 + ? = 20
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7
? + 6 = 20
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14
Fill in the part-whole model: whole = 20, one part = 8
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Other part = 12
Write two addition facts and two subtraction facts for the bond 15 + 5 = 20.
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15+5=20, 5+15=20, 20-5=15, 20-15=5
20 – 13 = ?
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7
More Addition Resources for Key Stage 1
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