Download Engage NY Module 1 - Mrs. Neubecker's 5th Grade

Engage NY Module 1
LESSON 10 – Objective: Subtract decimals
using place value strategies and relate those
to a written method.
Fluency Practice – Take out the Unit
 Say the number 76.358
 76 and 358 thousandths
 Write 76.358 in unit form
 7 tens, 6 ones, 3 tenths 5 hundredths, 8 thousandths
6358
 7 tens _______
thousandths
358
 7 tens 6 ones ______
thousandths
58
 763 tenths _____
thousandths
58 thousandths
 76 ones 3 tenths ____
7635 hundredths 8 thousandths
 _____
Fluency Practice – Add Decimals
5 tenths
 3 tenths + 2 tenths = ______
 How would the number sentence be written in decimal
form?

.3 + .2 = .5
9 hundredths
 5 hundredths + 4 hundredths = ___________
 How would the number sentence be written in decimal
form?

.05 + .04 = .09
39 hundredths
 35 hundredths + 4 hundredths = __________
 How would the number sentence be written in decimal
form?

.35 + .04 = .39
Fluency Practice – One Unit Less
 What is the decimal 1 less than 5 tenths (.5)?
 4 tenths (.4)
 What is the decimal 1 less than 5 hundredths (.05)?
 4 hundredths (.04)
 What is the decimal 1 less than 5 thousandths (.005)?
 4 thousandths (.004)
 What is the decimal 1 less than 7 hundredths (.07)?
 6 hundredths (.006)
 What is the decimal 1 less than 9 tenths (.9)?
 8 tenths (.8)
Fluency Practice – One Unit Less
 What is the decimal 1 thousandths less than 29 thousandths
(.029)?

28 thousandths (.028)
 What is the decimal 1 tenth less than 61 hundredths (.61)?
 51 hundredths (.51)
 What is the decimal 1 thousandths less than 61 thousandths
(.061)?

60 thousandths (.060) or 6 hundredths
 What is the decimal 1 hundredth less than 61 thousandths
(.061)?

51 thousandths (.051)
 What is the decimal 1 hundredth less than 549 thousandths
(.549)?

539 thousandths (.539)
Application Problem
 At the 2012 London Olympics, Michael Phelps won
the gold medal in the men’s 100 meter butterfly. He
swam the first 50 meters in 26.96 seconds. The
second 50 meters took him 25.39 seconds. What was
his total time?
Concept Development – Problem 1
 5 tenths – 3 tenths = ______
.5 - .3 = .2
 Explain your reasoning when solving this subtraction
sentence.

Since the units are alike we can just subtract. 5-3 = 2. This problem
is very similar to 5 ones minus 2 ones, 1 or 5 people minus 2 people;
the units may change but the basic fact 5-2=3 is always true.
Concept Development – Problem 1
 7 ones 5 thousandths – 2 ones 3 thousandths =
 Solve using a place value chart and record our thinking
vertically, using the algorithm.
7.005 – 2.003 = 5.002
7.005
-2.003
---------5.003
 What did you have to think about as you wrote the problem
vertically?

Like units are being subtracted, so my work should also show that. Ones
with ones and thousandths with thousandths.
Concept Development – Problem 1
 Solve 9 tens 5 tenths – 3 tenths = __
 Explain to your neighbor how you’ll solve this one.
 In word form, these units look similar, but they’re not. I’ll just
subtract 3 tenths from 5 tenths.
90.5 – 0.3
90.5
- 0.3
----90.2
Concept Development – Problem 2
 83 tenths – 6 ones 4 tenths = ______ How is this
problem different from the problems we’ve seen
previously? (8.3 – 6.4 = ____)

These problems will involve regrouping.
 What are some ways we could solve this problem?

Using disk on a place value chart or standard algorithm.
 Explain how you solved the problem.

I had to regroup before we could subtract tenths from tenths. I had to
borrow a whole group from the ones. A whole group is 10 tenths. I
added the 10 tenths to the 3 tenths to get 13 tenths. I then took 13
tenths minus 4 tenths. Then we subtracted ones from ones, using the
7 13
same process as whole numbers.
8.3
-6.4
-----1.9
Concept Development – Problem 2
8.3 – 6.4 = 1.9
Concept Development – Problem 2
 9.2 – 6 ones 4 tenths = ______ How is this problem
different from the problems we’ve seen previously? (9.2
– 6.4 = ____)

These problems will involve regrouping.
 What are some ways we could solve this problem?

Using disk on a place value chart or standard algorithm.
 Explain how you solved the problem.

I had to regroup before we could subtract tenths from tenths. I had to
borrow a whole group from the ones. A whole group is 10 tenths. I
added the 10 tenths to the 3 tenths to get 13 tenths. I then took 13
tenths minus 4 tenths. Then we subtracted ones from ones, using the
same process as whole numbers.
8 9.212
-6.4
-----2.8
Concept Development – Problem 2
9.2 – 6.4 = 2.8
Concept Development – Problem 3
 Solve the following problems using a place value chart or
the standard algorithm.


0.831 – 0.292 = 0.539
4.003 – 1.29 = 2.713


What do you notice about the thousandths place in 1.29?
6 – 4.08 = 1.92
7 12
2
0.83111
- 0.292
--------0.539
9
3 1010
4.003
- 1.290
-------2.713
6
1.29
9
5 1010
6.00
-4.08
------1.92
Concept Development – Problem 3
0.831 – 0.292 = 0.539
Concept Development – Problem 3
4.003 – 1.29 = 2.713
Concept Development – Problem 3
6 – 4.08 =
End of Lesson
 Problem Set
 Debrief
 Exit Ticket