RGPS Seminar for Parents (Revised)

Using The Model Method to Solve Word Problems
DrYeap Ban Har
Marshall Cavendish Institute
Singapore
Slides are available at www.banhar.blogspot.com
CollegioDagoberto Godoy, Santiago de Chile

The Curriculum (Ministry of Education 2006)

emphasis
thinking
The Curriculum (Ministry of Education 2006)

emphasis
visualization

Experiencing
Singapore Math

Kyla
?
$28 – $9 = $19
Kyla has $19.
Jake
?
$9
$28

Ming
48
Naomi
48 ÷ 4 = 12
3 x 12 = 36
Ming has 36 candies.

15
3 units  15
18 units  6 x 15 = 90
apples
There are 90 fruits in the basket.

Method 1
3 units  15
18 units  6 x 15 = 60 + 30 = 90
18 units  6 x 15 = 3 x 30 = 90
Method 2
3 units  15
1 unit  5
18 units  18 x 5 = 50 + 40 = 90
18 units  18 x 5 = 180 ÷ 2 = 90

Allan’s allowance = 4 x $8 = $32
$24 ÷ 3 = $8
$6
$18

Mon
Tue
$3
$100
Wed
$3
$3
Thu
$3
$3
$3
$100 – 6 x $3 = $82
$82 ÷ 4 = $20.50
$20.50 + 3 x $3 = $29.50
She saved $29.50 on Thursday.

adults
children
2 units  380 – 260 = 120
1 unit  60
260 – 60 = 200
200 + 200 = 400
400 people left at lunchtime.

apples
90
oranges
38
pears
15

apples
90
oranges
pears
15
23

90 + 15 = 105
5 units 
1 unit  105 ÷ 5 = 21
There were (21 + 21 + 23) apples, hence oranges.
There were 44 oranges used.
apples
?
oranges
pears
15
23

What if we have drawn 38 to be much longer?
apples
90
oranges
38
pears
15

What if we have drawn 38 to be much longer?
apples
105
oranges
38
pears
We still get 5 units  105

One other way to solve it …
Number of oranges left = x
Number of apples left = 2x
Number of pears left = 2x – 15
x + 2x + 2x – 15 = 90
5x = 105
x = 21
Number of pears left = 2 x 21 – 15 = 27
Number of pears at first = 38 + 27 = 65
Number of oranges at first = 65
Number of oranges used = 65 – x = 65 – 21 = 44

18%
342
24%
76%
76%  342
Mr Wong had 450 books at first.
1%  4.5
100%  450

Xueling + Siti (64)
Jane (16)
(24 – 16) units = 8 units
8 units = 14 shells
40 units = 5 x 14 shells
40 units = (50 + 20) shells
Xueling collected 70 shells.
Jane + Xueling
Siti
(24)
(40)

This problem requires the ability to visualize.

x + b + d = 180
b
x
d

y
e
y + c + e = 180
c

a
e
b
x
y
By the same logic:
x + b + d = 180
y + c + e = 180
z + a + d = 180
v + b + e = 180
w + a + c = 180
z
w
v
d
c
2a + 2 b + 2c + 2d + 2e + x + y + z + v + w = 5 x 180
x + y + z + v + w = 3 x 180
Hence, a + b + c + d + e = 180

DrYeap Ban Har
Marshall Cavendish Institute
Singapore

Mani has 245 ten-cent coins and 455 five-cent coins. Nina has 165 ten-cent coins and 135 five-cent coins. After Mani gives Nina some coins, of Mani’s coins are ten-cent ones and the ratio of the number of Nina’s five-cent coins to the number of her one-cent coins is 3 : 2.
They have only five-cent and one-cent coins.
Post Your Solutions on MCI’s Facebook
Find the number of coins Mani gives to Nina.

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RGPS Seminar for Parents (Revised)

by Jimmy Keng on Apr 23, 2011

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