Grades 1–2 (review in grade 3) · 1.NBT.4, 2.NBT.5, 2.NBT.7
How do I help my child with carrying in addition?
Addition with regrouping (carrying)
- 38 is three tens and eight ones. Add 5 ones and you have thirteen ones: a ten and three. The ten joins the tens. That's carrying, all of it.
- The little 1 over the next column just records that move. A child who drops it isn't forgetting a rule; they have not yet made a ten.
- So start with blocks, coins, or sticks and dots: ten ones bundle into a ten and move over. Paper comes after.
- Find your child's wrong answer below and you've found the rule they're using.
The five-minute check
A short run of problems on a phone or tablet, chosen as your child answers. If one of the three patterns is behind their mistakes, the check names it. Nothing to install, nothing stored.
Hand the phone over, or play it here. When it says all done, take it back and tap see what we found.
Start the five-minute checkThe three ways it goes wrong
- Forgets the ten 38 + 45 they write 73 it is 83 Adds each column and keeps only the ones digit of the total. The ten that should move left gets dropped.
- Writes the whole column sum 38 + 45 they write 713 it is 83 Writes each column's full total into the answer: 8 and 5 are 13, so 13 goes down; 3 and 4 are 7.
- Carries two columns over 375 + 182 they write 1457 it is 557 The carried ten skips a column and lands two places left, where it's worth a hundred.
What the school is probably doing
- Regrouping / composing a ten
- The written method, through tens and ones first; the small 1 records a ten being made.
- Expanded form
- 38 + 45 as 30 + 40 and 8 + 5: seventy and thirteen, then 83.
- Friendly numbers
- Take 2 from 45 to turn 38 into 40, then 40 + 43 = 83. No carrying at all, and the app plays it too.
- Base-ten blocks and drawings
- Sticks for tens, dots for ones. If your child draws these on homework, the lesson is working.
Questions parents ask
What grade is this?
Two-digit plus one-digit with a carry is grade 1 in the US (1.NBT.4); two-digit plus two-digit is grade 2 (2.NBT.5), three-digit later that year (2.NBT.7).
Is carrying the same as regrouping?
Yes. The word changed because nothing is carried anywhere: ten ones are regrouped into one ten. If carrying works at your kitchen table, use it.
My child writes 13 under the line. Is that bad?
It's honest, and the easiest pattern to fix. The adding is right; the child just hasn't learned that a column holds one digit. Ask where a ten lives.
The answers are always ten too small.
That's the forgotten ten, the most common pattern. Back to blocks for a few days: thirteen ones have to bundle, and the bundle has to go somewhere.
Should I teach the little 1?
Teach the bundle first; the little 1 is just how we write it down. A child who only knows the notation loses it as soon as the sum looks unfamiliar.
How long should we practise?
Five to ten minutes most days beats an hour on Sunday. Three or four sums done slowly with blocks are worth more than a page.
Cardinal Math watches for all of these, every day.
Inside the app the same patterns are caught as your child plays, across the whole of K to grade 5, and explained to you in plain words. One price, no ads, no streaks. Coming to iPhone and iPad.
Tell me when it's out