Basic Bar Models in Fractions
Presenter: Peggy Foo
August 5, 2014
1
Learning Outcomes
Participants will be able to
• 
Understand the rationale of model method as a
heuristic/ problem-solving tool
• 
Draw different types of models to solve word
problems related to fractions
2
Under ‘Processes’ component,
•  One of the heuristics is model method
•  Helps to visualize situations and Math problems
which are usually meant for secondary pupils
3
Origin
Developed by a project team in MOE in the
1980s
Objective: Help students who have great
difficulty with word problems in the early years
of primary school.
Drawing a pictorial model to represent
mathematical quantities (known and unknowns)
and their relationships given in a problem.
4
Guidelines
• 
• 
• 
• 
• 
Represent the problem using bar(s)
The bar(s) are best drawn proportionately
Fill in the diagram with all the given information
The unknown value/ answer is represented by
question mark
Interpret the model and write a simpler
mathematical statement
(e.g. 4 units è 20)
5
Part-Whole Model
♠ Shows various parts which make up a whole
♠ Find the whole by addition
♠ Find the other part by subtraction
6
Example 1
John ate 2/6 of a chocolate bar and his sister
ate 3/6 of it. How much of the chocolate bar
did they eat altogether?
7
Example 2
Cheryl ate 2/5 of a pie. Dennis ate 3/10 of the
same pie. What fraction of the pie was left?
8
Example 3
John has 20 marbles
He gave 3/5 of it to Peter.
How many marbles did John give to Peter?
9
Comparison Model
•  Show the relationship between 2 quantities
when they are compared
•  E.g. compared by showing the difference
10
Example 4
In a school, 5/6 of the pupils are girls.
If there are 480 more girls than boys, how many
pupils are there together?
11
Change/ Transforming Model
•  This type of model can be used to solve
complex problems
•  The parts can be transformed into smaller
units.
•  This type of model is useful for tacking
problems which involve before-and-after
situations.
12
Example 5
Mrs Chen made 120 cakes. She sold 3/4 of
them on Sunday and1/3 of the remainder on
Monday. How many cakes did she sell on
Monday?
13
Example 6
A seller sold 1/3 of his fishballs in the afternoon and
2/5 of the remainder in the evening. If he had 150
fishballs left, find the number of fishballs he had at
first.
14
Example 7
Jenny had $30 more than Tom at first. After Tom
spent 1/4 of his money and Jenny spent 1/2 of
her money, they were left with an equal amount
of money each. How much money did Jenny
have at first?
15