Mathematics Chapter 1: Addition & Subtraction with regrouping Grassy Lake Elementary School Third Grade Created by: Mrs. Tamara Russell.

MathematicsChapter 1: Addition &

Subtraction with regroupingGrassy Lake Elementary School Third Grade

Created by: Mrs. Tamara Russell

Goals To identify and write related addition and subtraction

facts. To solve number sentences for missing addends. To add 2-digit numbers without regrouping. To subtract 2-digit numbers without regrouping. To use the problem solving skill choose the

operation.

Materials Scrap paper or white boards Pencils or expo markers Erasers or paper towels for the boards

Today’s Lesson By the end of today’s lesson, you will be able to add

and subtract two digit numbers using regrouping.

56+1571

62- 1547

151

Lesson Did you know that every

number has a home, just like you?

We call those numbers homes their place value.

In order to add or subtract two digit numbers we need to review place value!

Let’s go!

Let’s do some problems! You will need a white board, a marker and an eraser. Together we will do six problems – three addition

and three subtraction. When we are all done, we should know how to add

and subtract by regrouping! Let’s do it!

Two digit addition Always remember to line up

your numbers properly. Start at the right. (6 + 5) Put the sum of 6 + 5 in its

house. (11) Oops! Too many! Carry a number!

Now, add the numbers in the tens’ column. (5 + 1 + 1)

Put the sum of 5 + 1 + 1 in the tens’ column. (7)

56

+ 15

Tens Ones

17

1

Again? Always remember to line up

your numbers properly. Start at the right. (4 + 6) Put the sum of 4 + 6 in its

house. (10) Oops! Too many! Carry a number!

Now, add the numbers in the tens’ column. (2 + 3 + 1)

Put the sum of 2 + 3 + 1 in the tens’ column. (6)

64

+ 32

Tens Ones

06

1

Last time? Always remember to line up

your numbers properly. Start at the right. (2 + 9) Put the sum of 2 + 9 in its

house. (11) Oops! Too many! Carry a number!

Now, add the numbers in the tens’ column. (3 + 1 + 1)

Put the sum of 3 + 1 + 1 in the tens’ column. (5)

92

+ 13

Tens Ones

15

1

Let’s subtract! Always remember to line up

your numbers properly. Start at the right. (3 - 4) Oops!

You can’t subtract 4 from 3! Time to borrow!

Borrow ten from next door and make 13. And subtract a ten to make 6.

Now, subtract. (13 – 4) Put your answer in the ones place.

Last, subtract 6 – 3. Put your answer in the tens place!

43

- 37

Tens Ones

93

136

Again? Always remember to line up

your numbers properly. Start at the right. (2 - 4) Oops!

You can’t subtract 4 from 2! Time to borrow!

Borrow ten from next door and make 12. And subtract a ten to make 6.

Now, subtract. (12 – 4) Put your answer in the ones place.

Last, subtract 3 – 2. Put your answer in the tens place!

42

- 24

Tens Ones

81

123

Last time! Always remember to line up your

numbers properly. Start at the right. (5 - 9) Oops! You

can’t subtract 5 from 9! Time to borrow!

Borrow ten from next door and make 15. And subtract a ten to make 7.

Now, subtract. (15 – 9) Put your answer in the ones place.

Last, subtract 7 – 7. The answer is zero and does not change the amount in the number, so you don’t have to put it there!

95

- 78

Tens Ones

6

157

Independent work Complete these practice

problems on your white board. Raise your hand when you are done so that I can check your work!

You have ten minutes to work and then I’ll show you the answers.

2 4 6 4+ 1 6 - 5 8

2 3 7 8+ 4 8 - 5 9

4 0

1

7 1

1

6

5 14

1 9

6 18

Fantastic!How did I get such smart cookies?

Tomorrow’s Lesson:Working on addition and subtraction

story problems