Mathematics

1
Mathematics

• Chapter 1 Addition Subtraction Concepts
• Grassy Lake Elementary School
• Third Grade
• Created by Mrs. Tamara Russell

2
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.

3
Materials

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

4
Todays Lesson

• By the end of todays lesson, you will be able to
  add and subtract two digit numbers without
  regrouping.

5
Vocabulary

• fact family a set of related addition and
  subtraction sentences.
• FOR EXAMPLE
• 7 8 15
• 8 7 15
• 15 - 7 8
• 15 - 8 7

6
Vocabulary

• inverse operations operations that undo each
  other
• FOR EXAMPLE
• Writing a fact family shows inverse operations.
• Do you remember how to write a fact family?
• Use the numbers 3, 5, 8.
• Show your work on your white board.

7
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!
• Lets go!

8
Review of place value

• Neighborhoods and numbers have a lot in common.
• Check out our number neighborhood!
• The place on the corner is the ones. The next
  house is the tens. The last house on this block
  is the hundreds place.
• Can you read the number?

3 5 6
9
Lets 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 without regrouping! ?
• Lets do it!

10
Two digit addition

• Always remember to line up your numbers properly.
• Start at the right. (4 2)
• Put the sum of 4 2 in its house. (6)
• Now, add the numbers in the tens column. (5 3)
• Put the sum of 5 3 in the tens column. (8)

4
5
2
3
6
8
11
Again?

• Always remember to line up your numbers properly.
• Start at the right. (1 3)
• Put the sum of 1 3 in its house. (4)
• Now, add the numbers in the tens column. (5 4)
• Put the sum of 5 4 in the tens column. (9)

1
5
3
4
4
9
12
Last time?

• Always remember to line up your numbers properly.
• Start at the right. (7 1)
• Put the sum of 7 1 in its house. (8)
• Now, add the numbers in the tens column. (3 2)
• Put the sum of 3 2 in the tens column. (5)

7
3
1
2
8
5
13
Lets subtract!

• Always remember to line up your numbers properly.
• Start at the right. (6 - 1)
• Put the difference of 6 - 1 in its house. (5)
• Now, subtract the numbers in the tens column. (6
  - 4)
• Put the difference of 6 - 4 in the tens column.
  (2)

6
6
1
- 4
5
2
14
Lets subtract, again!

• Always remember to line up your numbers properly.
• Start at the right. (4 - 2)
• Put the difference of 4 - 2 in its house. (2)
• Now, subtract the numbers in the tens column. (7
  - 1)
• Put the difference of 7 - 1 in the tens column.
  (6)

4
7
2
- 1
2
6
15
Last time!

• Always remember to line up your numbers properly.
• Start at the right. (2 - 1)
• Put the difference of 2 - 1 in its house. (1)
• Now, subtract the numbers in the tens column. (5
  - 3)
• Put the difference of 5 - 3 in the tens column.
  (2)

2
5
1
- 3
1
2
16
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 Ill show
  you the answers.

3 5 7 3
4 2 - 5 1

7 1 5 3
2 6 - 2 2

17
Wonderful!

• What fabulous mathematicians you are!
• Tomorrows Lesson
• Reviewing addition and subtraction with
  regrouping!