1. Mathematics Chapter 1: Problem Solving Skills
Today’s Lesson: Choose the operation
Created by: Mrs. 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. Today’s Lesson in all how many more?
By the end of today’s lesson, you will know at least three words that mean addition and three words that mean subtraction.
in all
how many more?

5. Lesson In all Are left How many more
Almost every story problem will have a word or phrase that gives away how to solve it.
Today, we will focus on a few addition and subtraction key words.

6. Let’s do some problems!
You will need a white board, a marker and an eraser.
Together we will do four practice problems.
Later, you will do four independent problems.
When we are all done, we should know how find key words in story problems to solve them! 
Let’s do it!

7. Create this chart on your board.
Addition Words
Subtraction Words

8. Look for the clue words & write them!
Tom rode his bike 12 miles in the morning and 8 miles in the afternoon. How far did Tom ride in all?
In all means addition!

9. Look for the clue words & write them!
There are 13 girls and 18 boys taking music lesson. How many children are taking music lessons?
How many means addition!

10. Look for the clue words & write them!
The school store had 48 dress shirts. It sold 27 shirts. How many shirts were left?
left means subtraction!

11. Look for the clue words & write them!
In one class there are 14 girls and 9 boys. How many more girls are there than boys?
How many more means subtract!

12. Independent Work
Susi planted 29 pansies and 33 marigolds. How many flowers did Susi plant in all?
What is the operation?
What is the number sentence I should write?
What is the answer to my problem?

13. Independent Work
Mrs. Chang had 24 apples. She used 6 in a pie. How many apples does she have left?
What is the operation?
What is the number sentence I should write?
What is the answer to my problem?

14. Last one!
There are 28 adults and 78 children at the puppet show. How many people are at the show?
What is the operation?
What is the number sentence I should write?
What is the answer to my problem?

15. You are so bright! For more practice, please work on PW6 at your desk!
Unbelievable!
You are so bright!
For more practice, please work on PW6 at your desk!