Subtraction Within 20
This topic covers 5 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
- Take away within 10
Subtract within 10 - Subtract from teens
Subtract from numbers 11-20 - Find difference
How many more or fewer? - Missing numbers
Find the missing number: 15 - ? = 8 - Mixed add & subtract
Combine addition and subtraction
Common Mistakes
- Subtracting the smaller digit from the larger regardless of position (e.g. for 12-5, doing 5-2=3)
In subtraction, order matters — you always start with the first number and take away the second. Use physical objects: put out 12 counters, then remove 5. How many are left? - Thinking subtraction always makes a small number (not recognising that 18-1=17 is still a big number)
Subtraction means "take away some," not "make small." Practise with examples where you subtract just 1 or 2 so children see the result can still be large.
Tips for Parents
- Act out subtraction stories: "There were 15 biscuits on the plate. Dad ate 4. How many are left?" Then actually remove biscuits and count.
- Use a number line and practise jumping backwards. Start at 14, jump back 3 — where do you land?
- Play "How many are hiding?" Put 12 toys on the table, cover some with a cloth, and ask your child how many are hidden.
- Connect subtraction to addition: "If 7+5=12, then 12-5 must be...?" This builds the relationship between the operations.
Key Words
- Subtract — Take one number away from another.
- Minus (−) — The symbol that means "take away."
- Difference — How far apart two numbers are — the difference between 8 and 5 is 3.
- Take away — Remove some from a group.
- Left — How many remain after taking some away.
Where This Fits
Before this topic: Children need to add within 20 confidently and understand that subtraction is the opposite of addition.
After this topic: Subtraction within 20 leads to subtraction within 100 in Year 2 and eventually to formal column subtraction.
How MathCraft Teaches This
In MathCraft, Subtraction Within 20 is taught through the Algebra & Arithmetic 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 5 steps, revisiting concepts your child finds tricky and advancing when they're ready. Parents can see detailed progress in the Parent Dashboard.
Practise Subtraction Within 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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