Second Grade · Math · week 11

Regrouping: trading ten ones for a ten

Understand and apply regrouping (composing a new ten) when adding 2-digit numbers.

Sometimes adding the ones makes more than 9, like 7 + 6 = 13. You cannot leave 13 ones sitting in the ones place, so you trade 10 of them for one new ten rod.

That trade is called regrouping. Write the 3 ones in the ones place, and carry the new ten over to the tens column to add in.

📋 For the teacher
Teach it (10–15 min):
  • Use real ones cubes: count out 13, then trade 10 of them in for a ten rod right in front of them -- the trade should be a hands-on action, not just a written rule.
  • Say the word "regroup" or the phrase "make a new ten" every time, so the vocabulary sticks alongside the action.
  • Watch that the carried ten actually gets added into the tens column, not forgotten.
  • Slow down here -- this is the biggest new idea of the trimester. Repetition with blocks pays off.
Talk about it:
  • What does it mean to "regroup" when adding?
  • Why can we not just write "13" in the ones place?
  • Where does the extra ten go after you regroup?

Mastery looks like: They regroup correctly when the ones sum exceeds 9, carrying a new ten into the tens column.

Common stumbles: Forgetting to add the carried ten; writing the whole two-digit ones sum (like "13") directly in the ones place.

See it visually

Interactive, spoken-aloud tools that show this idea in motion.

AdditionSee groups combine — with counters, blocks, and the number line.try →
Homework for this lessonType it, write it with a stylus, or print it for pencil & paper.open →
Records attendance + 15 min of Math for this learner.
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