1. NYS Math Module 1 Lesson 9
Objective: Add decimals using place value strategies and relate those strategies to a written method.
5.NBT.4 Round to different place values
5.NBT.1 Decompose the unit
5.NBT.7 Adding decimals

2. Sprint
****8 minutes****
Ready, Set
GO!!

3. 6.358 = 63 tenths ____ thousandths
Decomposing the Unit!
Think about money. How many dimes are there?
Say this number:
6.35
How many tenths are in 6.35?
63 tenths
6.358 = 63 tenths ____ thousandths 58

4. 7.354 = 73 tenths ____ thousandths
One more!
Say this number:
7.354
How many tenths are in 7.354?
73 tenths
7.354 = 73 tenths ____ thousandths 54

5. On your board, round to the nearest tenth.
Rounding!
Say this number:
2.475
On your board, round to the nearest tenth.
2.5

6. Round 2.457 to the nearest hundredth.
2.46

7. Round 2.987 to the nearest hundredth.
2.99

8. Round 2.987 to the nearest tenth.3

9. Oral Fluency
I’m going to show you a decimal, you need to say the decimal that is one tenth more.
0.5
0.7
0.9

10. Now, we are going to count by hundredths
Now, we are going to count by hundredths. Say the decimal that is one hundredth more than the given value.
0.05
0.07
0.09

11. Say the decimal that is two tenths more than the given value.
0.3
0.7
0.11
What is 1 tenth more than 35 hundredths?
Write down 35 hundredths, then add 1 tenth
0.45

12. 0.351 0.495 What is 1 thousandth more than 35 hundredths?
What is 1 hundredth more than 485 thousandths?
Remember to write the number first.
0.495

13. Share your answer with your partner.
Word Problem
Ten baseballs weigh 1,417.4 grams. About how much does 1 baseball weigh? Round your answer to the nearest tenth of a gram. Round your answer to the nearest gram. If someone asked you, “About how much does a baseball weigh?” which answer would you give them and why?
Share your answer with your partner.

14. Word Problem Solution

15. How is this problem the same as a whole number addition problem?
Adding Decimals
Let’s add 2 tenths plus 6 tenths using our place value charts.
8 tenths
Write the addition sentence on your board.
2 tenths + 6 tenths = 8 tenths
How is this problem the same as a whole number addition problem?
Turn to your partner and share.

16. Work with your partner to solve the next two problems on your place value chart.
2 ones 3 thousandths + 6 ones 1 thousandth
= 8.004
2 tenths 3 thousandths + 6 hundredths
0.203
0.060
0.263 +
Let’s write it vertically!

17. Let’s look at the following problem:
tenths
How would you write 13 tenths?
Write it on your white board.
13 tenths = 1.3
Draw a picture to represent 13 tenths. You may use your place value chart.
Share with your partner
Solve: tenths
3.1

18. Let’s write it vertically!
Another way to add and subtract decimals.
Tip #1 - ALWAYS line up the decimal! This means the decimals are one on top of another.
Tip #2 – Add ZEROS in all the empty spaces.
Let’s give it a try.
0.74
0.59
1.33 +
Let’s write it vertically!

19. Try solving the last two problems.
12.244
8.214

20. Thank you for downloading this presentation.
Backgrounds, clip art, and font by:.
Laura Strickland
Clip art from Colleen Alaniz- Totally Terrific in Texas
The following pages are from NYS Math Modules. I minimized the images to reduce the paper waste and thought they may be helpful to others as well. For the entire module visit:

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