MathGrade 2ages 7–8
🥣 Take away to 20
A child who solves 15 − 7 by adding, landing on 22, hasn't mixed up their facts — they've mixed up the direction the problem is asking them to move in.
Try this lesson freeNo card needed. The first lesson is free.
Download on the App StoreWhat your child learns
- Subtract means take away. The number gets smaller.
- 15 − 7: count back seven times to 8.
- Not 15 + 7. Adding would grow to 22.
- Or split: 15 − 5 = 10, two more, 8 left.
The mistake most kids make here
Adding instead of taking away.
Try one question
15 − 7
- 8
- 22
- 7
Answer
8 — Yes. Eight — less than you started with.
How Maya teaches it
Your child tells Maya what they did in class. She teaches this topic at her desk, asks questions with tappable answers, and when the answer is wrong she explains why that answer was tempting instead of saying “try again”. She remembers what did not land and comes back to it.
Your child has it when they can: 15 − 7 without adding to 22.
How to help at home
"Take away" and "add" both involve two numbers and an answer, so a child who is unsure which sign means what can default to the operation they know best — usually addition, since it's often taught first and practiced more.
Lay out 15 small objects — crackers, coins, blocks. Ask your child to physically remove 7 of them and count what's left. Watching the pile shrink to 8, not grow to 22, makes the direction of subtraction impossible to miss.
If 22 comes up as an answer, ask: "if we started with 15 things and took some away, could we end up with more than we started?" That question alone often catches the error before you explain anything.
A sign they've got it: they can predict, before counting, whether an answer to a subtraction problem should be bigger or smaller than the number they started with.
Questions parents ask
- Why does my child add instead of subtract?
- This often happens when a child recognizes the numbers in a subtraction problem but isn't yet reliably reading the minus sign as "take away, get smaller." Addition can be the more automatic, practiced response.
- How can I tell if my child understands subtraction or is just guessing?
- Ask them to predict, before solving, whether the answer will be bigger or smaller than the starting number. A child who understands subtraction will say "smaller" every time, even before doing the arithmetic.
- Is counting back a good strategy for numbers like 15 − 7?
- Yes — counting back seven steps from 15 works well for smaller numbers. Splitting the subtraction (15 − 5 = 10, then 10 − 2 = 8) is a useful next step once counting back is solid.
- How does Maya teach subtraction within 20?
- Maya has the child act out taking objects away and watch the pile shrink before introducing counting-back or splitting strategies, so the meaning of "subtract" is anchored first.
No card needed. The first lesson is free.
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