how does thinking about number paths help you add and subtract … · 2015-11-29 · ©urriculum...

©Curriculum Associates, LLC Copying is not permitted. 21Lesson 3 Understand Mental Math Strategies (Make a Ten)

Name:

How does thinking about number paths help you add and subtract in your head?

Study the example showing the make a ten strategy on a number path. Then solve Problems 1–6.

1 Make a ten to add 9 1 6 First write all the number partners of 6

2 Make a ten Fill in the missing numbers

9 1 6 5 ?

9 1 5 10 and 10 1 5

So, 9 1 6 5

Example

Add 8 1 5

Think of a number path Start at 8 Add 2 to make 10

You need to add 3 more

5 5 2 1 3

So, 8 1 5 5 13

Lesson 3

Understand Mental Math Strategies (Make a Ten)

7 8 9 10 11 12 13

2 3

9 10 11 12 13 14 15

©Curriculum Associates, LLC Copying is not permitted.22 Lesson 3 Understand Mental Math Strategies (Make a Ten)

Solve.

3 Subtract Fill in the missing numbers

11 2 4 5 ?

4 5 3 1 1

So, 11 2 4 5

4 Use 2 and 2 for the number partners instead in Problem 3 What is different?

5 Subtract Fill in the missing numbers

14 2 8 5 ?

8 5 1

So, 14 2 8 5

6 How is making a ten to add the same as making a ten to subtract? How is it different?

6 7 8 9 10 11 12

65 7 8 9 10 11 12 13 14


Name:

Explore the Make a Ten Strategy

Study how the example shows making a ten to add. Then solve Problems 1–6.

1 Fill in the missing numbers to find 9 1 4

9 1 4 5 ?

9 1 1

So, 9 1 4 5

2 Look at the open number line in Problem 1 How would you change the numbers to show 9 1 5?

Example

8 1 7 5 ?

8 1 2 1 ?

The partners 8 and 2 make 10

8 1 7 5 ?

8 1 2 1 5

Add 5, the other partner of 7

So, 8 1 7 5 15

Lesson 3

8 10

2

8 10 15

2 5

9 10


Solve.

3 Make a ten to subtract Fill in the missing numbers to show 12 2 4 5 8

4 Complete the number sentences

12 2 5 10 16 2 5 10

13 2 5 10 15 2 5 10

5 Fill in the missing numbers to find 15 2 9

15 2 9 5 ?

15 2 9 5

6 Jan circled the problems that she cannot solve in her head by making a ten

14 2 7 8 2 2 12 2 8 9 2 4 15 2 6

Look at all of the problems Why doesn’t Jan make a ten to solve the circled problems?

8 10 12

10 15


Name:

Reason and Write

Look at the example. Underline a part that you think makes it a good answer.

Example

1 Write an addition sentence you can solve by making a ten

2 Describe the steps for making a ten to add Write three or four steps You can use words and pictures

1 5

Step 1 Start at 8. Add a number to 8 to make 10. The number to add is 2. 8 1 2 5 10.

Step 2 Use 2 as a partner. Find the other partner that makes 6. The partners are 2 and 4.

Step 3 Think of moving 2 places on a number line from 8 to 10. Then move 4 more places from 10 to 14.

8 10 14

2 4

Step 4 The number you end at is your answer. It is 14.

Lesson 3

8 6 14Where does the example . . .• show the

addition sentence?

• use words to explain?

• use numbers to explain?

• use a picture to explain?


Solve the problem. Use what you learned from the example.

1 Write a subtraction sentence you can solve by making a ten

2 Describe the steps for making a ten to subtract Write three or four steps You can use words and pictures

Show your work. Did you . . .• show the

addition sentence?

• use words to explain?

• use numbers to explain?

• use a picture to explain?

how does thinking about number paths help you add and subtract … · 2015-11-29 · ©urriculum...

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