Unit 8
A C T I V I T Y 40
AC TIVIT Y
30 MIN
Division as Repeated Subtraction
Use after
Unit 8, Session 4.5
Vocabulary/Vocabulario
repeated subtraction/
resta repetida
Materials/Materiales
• overhead counters/
transparencias de fichas
• Activity 40 Master (see below)/
Actividad 40 (ver abajo)
CVbZ
Partners, Teams, and Paper Clips
?L?I?EDÅ7IÅÅ
;F;7J;:ÅK8JH79J?ED
NOTE Students match a repeated
subtraction with the correct division
problem. Then they write the letter of
the problem to find the mystery word.
BViX]ZVX]gZeZViZYhjWigVXi^dcl^i]i]Z
XdggZXiY^k^h^dcegdWaZb#Lg^iZi]ZaZiiZgd[
i]ZegdWaZbVWdkZ^ihbViX]idÄcYi]Z
bnhiZgnldgY#
&
K
'
-'+
+')
)''
''%
© Pearson Education, Inc. 2
)
>
(
&%**
**%
D
*
&%'-'+
+')
)''
''%
9
'%*&*
&**&%
&%**
**%
Students should understand that each time they
subtract 2, it is like putting 2 apples in a bag. How
many goodie bags can we make using 8 apples?
The process of subtracting off the same number as
far as you can go is called repeated subtraction.
8⫺2⫽6
6⫺2⫽4
4⫺2⫽2
2⫺2⫽0
8⫼2⫽4
Now let’s suppose you begin with 11 apples. Let’s use repeated subtraction to
figure out how many goodie bags, each with 2 apples, you can make using the
11 apples. How would you solve this problem?
Activity 40
MASTER
9ViZ
Un i t 8
Display 8 overhead counters. Suppose you have
8 apples, and you want to make party goodie bags
that have 2 apples each. We can use subtraction to
find how many goodie bags we will need. Explain
that students could subtract off two counters at a
time until all the counters are used up.
CLASS
C
-))
))%
+
Students might say:
“I crossed out 2 apples and pretended to put them
in a bag. I continued crossing out 2 and pretending to
put them in a bag until I had just 1 apple left. You only
make 5 bags with the 11 apples with 1 apple left over.”
H
+')
)''
''%
BnhiZgnLdgY/
1
'%*) &%*' -') &%*' +'( &%*' &%'* -)'
Use after Unit 8, Session 4.5
11
9
7
5
3
⫺
⫺
⫺
⫺
⫺
2
2
2
2
2
⫽
⫽
⫽
⫽
⫽
9
7
5
3
1
Show the repeated subtraction for the above problem as shown at right.
Write 14 ⫼ 4 on the board. Use repeated subtraction to solve this problem. Explain
your answer. Give students an opportunity to demonstrate their answers using the
overhead counters and to explain what the remainder of 2 means. Have students write
the repeated subtraction.
PR AC TICE
© Pearson Education, Inc. 2
In the Activity 40 Master, students match each repeated subtraction problem with
the correct division problem. Then they write the letter of the problem above the
corresponding division sentence to find the mystery word.
DIFFERENTIATION : Suppor ting the Range of Learner s
Place students into pairs and give each group three decks of cards
(each deck should be on a different color paper. Deck 1 has division problems written
as repeated subtraction problems (such as 12 ⫺ 6 ⫽ 6; 6 ⫺ 6 ⫽ 0). Deck 2 has the
matching division problems (12 ⫼ 6 ⫽ 2). Deck 3 has a matching word problem
(6 students equally share 12 pencils. How many pencils does each student get?).
Have students find the three matching cards for each problem.
Unit 8: Partners, Teams, and Paper Clips
Session 4.5 (End-of-Unit Assessment)