Build it up, piece by piece.
Smile-sized sums
One little step up
Tiny adds, big smile
First steps
Build mental math
10 sums · +1
10 sums · +2
10 sums · +5 anything
10 sums · jump a ten
20 friendly sums
10 round-then-back
20 sums in the teens
20 over-the-ten
20 sums over 15
20 over-the-twenty
25 sums in the tens
16 close-to-twenty
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