Why place value comes before addition, not after
A child can add single-digit numbers correctly by counting on fingers without ever understanding that '23' means two groups of ten and three ones. That gap doesn't show up until carrying appears — and then it shows up as a wall, not a wobble.
If your child can solve 23+5 but freezes on 27+5, that's usually not a carrying problem — it's a place value gap. They don't yet see the '2' and the '3' as separate, different-sized quantities.
Teach it with objects before symbols
Bundle ten craft sticks with a rubber band and call it 'one ten.' Loose sticks are 'ones.' Building the number 23 becomes two ten-bundles and three loose sticks — a physical fact your child can see and touch, not an abstract rule to memorize.
Only after your child can build several numbers this way with objects should you move to place value charts or written column headings — the written version should describe something they already understand, not introduce something brand new.
Connecting place value to carrying, concretely
When ten loose sticks pile up during a problem, physically bundle them into a new ten and move it to the tens column. This turns 'carrying the 1' from a mysterious rule into something your child just did with their own hands.
Do this with objects for several problems before ever writing a small '1' above the tens column — the written shorthand only makes sense once the physical action behind it is familiar.
Signs your child has actually understood it
Ask your child to break apart a two-digit number in more than one way — 23 as 2 tens and 3 ones, but also as 1 ten and 13 ones. A child who's memorized a procedure struggles here; a child who understands place value finds it easy.
Another good check: ask which digit matters more for the size of a number, the tens or the ones, and why. A confident, reasoned answer — not just a guess — is the real signal to move forward.
Moving on to three digits and beyond
Once two-digit place value feels solid, hundreds are just 'ten groups of ten' — the same bundling idea repeated one more level up, not a new concept.
Resist the urge to rush this stage because two-digit problems 'look easy' — a shaky place value foundation is one of the most common reasons kids hit a wall in third or fourth grade math, long after addition worksheets stopped seeming like the hard part.