This is a complete lesson about how to teach regrouping in subtraction (borrowing) step-by-step with 2-digit numbers, meant for 2nd grade. The lesson contains a teaching video, instruction with visual models, and many exercises.

In the video below, I explain an idea of breaking down the concept of regrouping (borrowing) so that students can see what actually happens in it. For example, to subtract 52 − 38, we write 52 as 50 + 2 (breaking it down into its tens and ones). Then, regrouping means that 50 + 2 becomes 40 + 12. This makes the process totally transparent.

We will now study regrouping
(also called "borrowing") in subtraction.

As a first step, we study
breaking
a ten-pillar into ten little cubes.
This is called regrouping,
because one ten "changes
groups" from the tens group
into the ones.

Break a ten.

4 tens 5 ones

3 tens 15 ones

First we have 45. We
"break" one ten-pillar
into little cubes.

Now we have 3 tens and
15 ones. It is still 45, but
written in a different way.

Here is another example. First
we have 5 tens 3 ones. We
"break" one ten-pillar into
10 little cubes. We end up with
4 tens 13 ones.

Break a ten.

5 tens 3 ones

4 tens 13 ones

1. Break a ten
into 10 ones. What do you get? Draw or use manipulatives to help.

a.

3 tens 0 ones

___tens ____ones

b.

___ tens ____ones

___ tens ____ones

c.

___ tens ____ones

___tens ____ones

d.

___ tens ____ones

___ tens ____ones

e.

___ tens ____ones

___tens ____ones

f.

___ tens ____ones

___ tens ____ones

Let's study subtraction. The pictures on the right illustrate 45 − 17.

First, a ten is broken into 10 ones. So, 4 tens 5 ones becomes 3 tens 15 ones.

After that, cross out (subtract)
1 ten 7 ones.

Break a ten.

4 tens 5 ones

3 tens 15 ones

Cross out 1 ten 7 ones (from the second
picture).

What is left? ____ tens
____ ones

The pictures on the right illustrate
52 − 39.

First, a ten is broken into 10 ones. So, 5 tens 2 ones becomes
4 tens 12 ones.

After that, cross out (subtract)
3 tens 9 ones.

Break a ten.

5 tens 2 ones

4 tens 12 ones

Cross out 3 tens 9 ones (from the second
picture).

What is left? ____ tens ____ ones

2. Fill in. Always subtract (cross out some) from the second picture.

Break a ten.

3 tens 6 ones

2 tens 16 ones

a. Subtract
8
ones (from the second
picture).

What is left? ____ tens ____ ones

Break
a ten.

___ tens ___ ones

___ tens ___ ones

b.
Subtract 2 tens 7
ones.

What is left? ____ tens ____ ones

Break
a ten.

___ tens ___ ones

___ tens ___ ones

c. Cross out
2 tens 5 ones.

What is left? ____ tens ____ ones

Break
a ten.

___ tens ___ ones

___ tens ___ ones

d.
Cross out 4 tens 4
ones.

What is left? ____ tens ____ ones

3.
First, break a ten. Then subtract ones and tens separately.
Look at the example.

a.

5 tens 5 ones

4 tens

15 ones

−

3 tens

7 ones

1
ten

8 ones

b.

7 tens 2 ones

___ tens

___ ones

−

3 tens

5 ones

___ tens

___ ones

c.

6 tens 0 ones

___ tens

___ ones

−

2 tens

7 ones

___ tens

___ ones

d.

6 tens 4 ones

___ tens

___ ones

−

3 tens

8 ones

___ tens

___ ones

e.

7 tens 6 ones

___ tens

___ ones

−

4 tens

7 ones

___ tens

___ ones

f.

5 tens 0 ones

___ tens

___ ones

−

2 tens

2 ones

___ tens

___ ones

g.

8 tens 1 one

___ tens

___ ones

−

6 tens

5 ones

___ tens

___ ones

h.

6 tens 3 ones

___ tens

___ ones

−

2 tens

8 ones

___ tens

___ ones

4. Jessica had 27 colored pencils and her brother and sister had none. Then Jessica gave
10 of them to her brother, and four to her sister.

a.How many pencils does Jessica have now?

b. How many more pencils does Jessica have than her brother?

c. How many more pencils does Jessica have than her sister?

A self-teaching worktext for 2nd grade that covers mental addition and subtraction with two-digit numbers, and regrouping in addition and subtraction (carrying & borrowing).

Download ($5.65). Also available as a printed copy.

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