Make the exchange visible
Build 47 + 38 with tens and ones. The 15 ones become 1 ten and 5 ones. Move the new ten into the tens column before recording the written method.
Connect the model to the notation
Add 7 + 8 = 15, write 5 in the ones place, and mark 1 new ten above the tens column. Then add 4 + 3 + 1 = 8 tens, giving 85.
- Align ones below ones and tens below tens.
- Add the ones and exchange 10 ones for 1 ten.
- Add every ten, including the regrouped ten.
- Estimate to check that the sum is reasonable.
Work a sum that crosses 100
For 68 + 57, add 8 + 7 = 15, write 5 ones, and regroup 1 ten. Then 6 tens + 5 tens + 1 ten = 12 tens, so the total is 125.
Diagnose errors precisely
An answer of 75 often means the regrouped ten was omitted. An answer written as 715 may mean the learner has not exchanged 10 ones. Return to the place-value model for the specific step that broke down.
Check for understanding
Before solving 56 + 29, ask whether regrouping is needed and why. After solving, ask what the small 1 represents and why the answer 85 is reasonable.
Plan the lesson and practice
Review one no-regrouping sum, model an exchange with tens and ones, connect it to the written method, and solve one example together. Then use a short regrouping page and discuss one error or check at the end.