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North View Primary School1
Model Drawing(Basics)
North View Primary School
• Models are pictorial representations (i.e. bar diagrams) drawn to represent the data in a problem sum.
• It allows us to visualize the relationship between the parts and/or whole in a problem sum.
Model Drawing
North View Primary School
Problem Solving Tips
• Read the question carefully.
• Underline important information.
• Transfer the information/data into a model.
• Use a ? to represent the unknown data.
• Label the model with names of the people/things in the question.
North View Primary School
Types of Models• Part-whole (i.e. for one person)
Ali
Ali
Don
• Comparison (i.e. for comparison between two people)
30 stamps
?
30 stamps
?
Don has as
many stamps as Ali.
3
2
North View Primary School
Part-whole model
• A box of cereal costs $7. How many such boxes of cereal can Kelly buy with $42?
$42
$7
• $42 ÷ $7 = 6
She can buy 6 boxes of cereal.
? boxes
North View Primary School
Comparison Model
• Bala has the amount of money Alyssa has.
Bala has thrice the amount of money Catherine has. If the total amount of money they have is $50, how much money does Alyssa have?
2
1
B
C
A
$50
?
North View Primary School
10 units $50
1 unit $50 ÷ 10
= $5
B
C
A
$50
?
6 units $5 x 6
= $ 30
She has $30.
North View Primary School
Other models
• ‘Stack Up’ Model
• ‘Constant Difference’ Model
• Before & After Model
These models are improvisation of the part-whole and/or comparison models.
North View Primary School
‘Stack Up’ Model• 2 dictionaries and 4 novels cost $90.
Each dictionary cost thrice as much as each novel. How much did each dictionary cost?
D
$90
?
N
D
NNN
North View Primary School
N
D
$90
?
D
NNN
10 units $90
1 unit $90 ÷ 10
= $9
3 units $9 x 3
= $ 27
Each dictionary cost $27.
North View Primary School
‘Constant Difference’ Model
• There was 14 kg of rice in Box A and 2 kg of rice in Box B. Tommy added an equal amount of rice into each box. Now there are 5 times as much rice in Box A as in Box B. How much rice is there in Box A in the end?
Box A
14 kg
Box B
2 kg 12 kg
North View Primary School
There is 15 kg of rice in Box A.
4 units 12 kg
1 unit 12 kg ÷ 4
= 3 kg
Box A
14 kg
Box B
2 kg 12 kg
14 kg – 2 kg = 12 kg 5 units 3 kg x 5
= 15 kg
?
North View Primary School
Before & After Model
John
?
Ivan
• John and Ivan had an equal number of sweets. After John gave away 36 sweets, Ivan had 5 times as many stamps as John. How many stamps did Ivan have?
36
John
IvanBefore
After
North View Primary School
John
Ivan
?
36
Ivan had 45 sweets.
4 units 36
1 unit 36 ÷ 4
= 95 units 9 x 5
= 45