wunder beta💡 Why Addition Strategies Work
Go beyond getting the right answer and explain why your tricks work — like why splitting numbers into tens and ones, or adding one too many and taking it back, always comes out right.
What you’ll learn
- Why the Tricks WorkExplain why place-value splitting and compensation strategies give the correct answer.Splitting 46 + 37 into tens and ones works because each number is exactly its tens plus its ones, so no piece is lost or added. The 'add 10, take 1 back' trick works because 9 is 10 − 1: you overshoot by one on purpose, then remove it. Understanding the reason lets you trust the trick.
Questions this course answers
Why can you add the tens and ones separately in 46 + 37?
Each number is its tens plus its ones, so grouping them just reorders the same pieces.
To add 46 + 9, why is it smart to add 10 and then subtract 1?
9 is one less than 10, so adding 10 overshoots by exactly 1, which you take back.
In the 'add 10, take 1 back' trick, why do you subtract the 1?
Using 10 instead of 9 adds one extra, so removing 1 corrects it.
Adding numbers in any order is allowed because...
Order does not change a sum, so you can rearrange to make it easier.
What makes an explanation of a strategy a GOOD one?
A good explanation gives the reason, like 'nothing is lost' or '9 is 10 − 1'.
Grounded in trusted sources
- Khan Academy Kids
- PBS Kids — early math
- NAEYC — early math learning
- Britannica Kids
Every Wunder lesson is built from real, reputable sources — never invented.
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