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2nd Grade Addition & Subtraction
Regrouping only makes sense once students understand that a ten can be exchanged for ten ones (and the reverse). Teaching a written method before that concept is solid leads to memorized steps that break down on harder problems. Common Core 2nd grade expectations center on concrete models, drawings, and place-value strategies connected to a written method — fluency with the standard algorithm itself is generally a 4th grade expectation.
Where This Skill Fits
Addition and subtraction with regrouping is the central focus of 2nd grade math. It extends the addition/subtraction within 20 built in 1st grade to multi-digit numbers, and it depends entirely on place-value understanding.
Prerequisite Skills
- Addition and subtraction fluency within 20
- Understanding of tens and ones (place value to 100)
- Ability to represent a two-digit number with base-ten blocks
Recommended Conceptual Progression
- Add two-digit numbers without regrouping (concrete, then abstract)
- Add two-digit numbers with regrouping using base-ten blocks
- Record the regrouping process on a place-value chart
- Connect the chart to an efficient written method
- Repeat the same progression for subtraction with regrouping
- Extend to three-digit numbers
Common Student Misconceptions
- Treating regrouping as an arbitrary "borrowing" rule instead of exchanging value between places.
- Subtracting the smaller digit from the larger digit in each column regardless of which number is on top (e.g., computing 52 − 27 as 5 in the ones place).
- Forgetting to adjust the tens digit after regrouping a hundred, or the hundreds digit after regrouping a thousand.
Recommended Visual Models
- Base-ten blocks — for physically exchanging a ten for ten ones
- Place-value charts — for recording the exchange before writing the algorithm
- Open number lines — for an alternative addition/subtraction strategy that doesn't require regrouping
Small-Group Teaching Sequence
Model building the problem with base-ten blocks and narrate the exchange, guide students through building and recording a new problem together, then have students solve independently with blocks or a chart available.
I Do Example
"I have 3 tens and 2 ones, and I need to subtract 5 ones. I don't have enough ones, so I'll exchange one ten for 10 ones. Now I have 2 tens and 12 ones. 12 − 5 = 7." (Teacher models with blocks and a place-value chart side by side.)
We Do Example
"Let's solve 41 − 26 together. Do we have enough ones to subtract 6? What do we need to do?" (Teacher and students exchange a ten together, then complete the subtraction.)
You Do Example
Students solve 53 − 28 independently using blocks or a place-value chart, then record an efficient written method alongside their concrete work.
Quick Check
Two regrouping problems (one addition, one subtraction), checking whether the student can explain why they're exchanging a ten, not just complete the steps.
If the Student Is Ready
Move to three-digit regrouping, or regrouping across a zero (e.g., 300 − 148), which requires exchanging twice.
If the Student Is Not Ready
Return to base-ten blocks for two-digit regrouping and confirm the student can represent a two-digit number with tens and ones before reintroducing the algorithm.
Related Skills
- Before: Addition and subtraction within 20 (1st grade)
- Current: Addition and subtraction with regrouping
- Next: Multi-digit multiplication and division (3rd grade)
Relevant SMS Resources
- 2nd Grade Addition & Subtraction Bundle | Small Group Math Routines
- 2nd Grade Addition With Regrouping | Base Ten Small Group Lesson
- 2nd Grade Subtraction With Regrouping | Small Group Math Routine
Browse more 2nd grade regrouping routines, task cards, and quick checks in the full catalog.
Related Guides
- A 3-Digit Regrouping Math Routine
- 2nd Grade Small Group Math
- Teaching Addition With Regrouping in 2nd Grade Small Groups
- Teaching Subtraction With Regrouping in 2nd Grade Small Groups
- Teaching Place Value in 2nd Grade Small Groups
- Teaching Addition & Subtraction Word Problems
- Teaching Make Ten in 1st Grade Small Groups
- The Small Group Math Framework
Teacher FAQ
Should I teach "bottom bigger" as a shortcut?
No — that rule breaks down as soon as students see a problem where the top digit is smaller and reinforces treating digits independently instead of understanding place value. Teach the exchange conceptually instead.
How long should students use blocks before moving to the algorithm?
Until they can explain, in their own words, why they're exchanging a ten for ten ones — not just complete the steps correctly.