Number Bonds to 20
This topic covers 3 learning steps, guiding your child from the basics through to confident problem-solving. Each step includes a worked example and adaptive practice questions.
What Your Child Will Learn
- Bonds to 10
Find pairs that make 10 - Bonds to 20
Find pairs that make 20 - Missing Numbers
Find the missing part
Common Mistakes
- Relying on finger counting instead of instant recall (e.g. always counting on from 13 to reach 20)
By Year 2, number bonds to 20 should become automatic facts, not counted each time. Regular short practice — even 5 minutes a day — builds this fluency faster than occasional long sessions. - Not applying bonds to 10 when working out bonds to 20 (e.g. not seeing that 14+6=20 is related to 4+6=10)
Show the connection explicitly: "If 4+6=10, then 14+6 must be 20 — just add 10 to everything!" This pattern-spotting is key to mental maths.
Tips for Parents
- Play "Twenty Ping-Pong" — you say a number, your child says what makes 20. Take turns and speed up gradually.
- Use two sets of digit cards (0-20). Flip two cards — if they make 20, you win the pair. First to collect 5 pairs wins.
- In the car: "I'm thinking of a number. I add it to 13 and get 20. What's my number?"
- Write bonds on sticky notes and hide them around the house. Your child hunts for them and checks if each bond is correct.
Key Words
- Number bond — Two numbers that add together to make a given total.
- Recall — Knowing a fact instantly without having to work it out.
- Inverse — The opposite operation — if 13+7=20, then 20−7=13.
- Partition — Split a number into parts — 15 can be partitioned into 10 and 5.
Where This Fits
Before this topic: Children should have automatic recall of number bonds to 10.
After this topic: Number bonds to 20 support mental addition and subtraction within 100, and lay the groundwork for bonds to 100 in Year 3.
How MathCraft Teaches This
In MathCraft, Number Bonds to 20 is taught through the Geometry & Shape adventure track. Your child follows guided lessons with friendly characters, works through examples step by step, then practises with questions that adapt to their level.
The adaptive engine tracks mastery across all 3 steps, revisiting concepts your child finds tricky and advancing when they're ready. Parents can see detailed progress in the Parent Dashboard.
Practise Number Bonds to 20 with MathCraft
Step-by-step lessons, worked examples, and adaptive practice — all wrapped in an adventure game your child will love.
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