AC9M2N06_E1
Interpret everyday additive and multiplicative situations, choose an appropriate operation and explain why the operation matches the problem.
Chapter 6 • AC9M2N06
Help your child solve practical problems involving money, calendars, teams, sharing, equal groups and everyday decisions. This parent-friendly guide explains how children represent situations, choose suitable operations and communicate solutions before completing the printable activities aligned with AC9M2N06.
Mathematical modelling means using mathematics to understand and solve practical situations.
Children learn that solving a real-life problem involves more than completing a calculation. They need to understand the situation, decide which information is important, choose a suitable operation and explain what the answer means.
The practical situations in this unit may involve:
Children may use addition, subtraction, multiplication or division depending on the relationship between the quantities.
These activities support Australian Curriculum Version 9.0 content descriptor AC9M2N06 and its associated elaborations.
Use mathematical modelling to solve practical problems involving additive and multiplicative situations, including money transactions; represent situations and choose calculation strategies; interpret and communicate solutions in terms of the situation.
Interpret everyday additive and multiplicative situations, choose an appropriate operation and explain why the operation matches the problem.
Model and solve simple money problems involving whole dollar amounts using addition, subtraction, multiplication or division.
Solve practical problems involving teams, groups, sharing, food and whole-dollar amounts, including deciding what to do when there is a remainder.
Use a calendar to model and solve the question, “How many days are there left in this year?”
Model equal grouping and sharing situations presented through First Nations Australian children’s instructive games, represent relationships with number sentences and communicate solutions in context.
Children should understand why they are adding, subtracting, multiplying or dividing instead of choosing an operation from a single keyword.
For example, a shopping problem might require:
A complete solution should include the calculation and an explanation of what the answer represents.
Children will learn to:
I can explain what the problem is asking.
I can identify the known and unknown information.
I can represent the situation with a drawing or diagram.
I can write a matching number sentence.
I can choose an appropriate operation.
I can explain why I chose that operation.
I can solve a whole-dollar money problem.
I can form equal teams or groups.
I can share a quantity equally.
I can decide what to do with a remainder.
I can use a calendar to count days.
I can explain what my answer means.
Teachers encourage children to think about the meaning of a problem before beginning a calculation.
At home, follow this sequence: understand it, represent it, choose, calculate, check and explain.
Ask your child to read the problem and explain it in their own words.
Avoid beginning with: “Is this addition or subtraction?”
Instead ask:
Children who cannot retell the problem may not yet understand the situation well enough to choose an operation.
Underline or list the quantities that are known.
Circle or describe the unknown quantity.
For example:
“A child has $20 and spends $7. How much money remains?”
Additive situations involve joining, separating or comparing quantities.
Multiplicative situations involve repeated equal quantities, equal groups or sharing.
Examples:
Ask your child to explain why the chosen operation matches the relationship in the problem.
“I used subtraction because I knew the total and one part, and I needed to find the missing part.”
Other explanations may include:
Children may represent practical problems using:
A representation should show the mathematical relationship, not simply decorate the page.
Create a pretend shop using whole-dollar prices.
Ask questions such as:
Encourage your child to explain which operation is needed for each question.
Example:
“A book costs $8 and a game costs $12. What is the total cost?”
The amounts are being combined:
$8 + $12 = $20
The answer should be communicated as: “The total cost is $20.”
Example:
“Sam has $30 and spends $18. How much money remains?”
The amount spent is removed from the starting total:
$30 − $18 = $12
The answer is: “Sam has $12 remaining.”
Example:
“Each of 6 children contributes $5. How much money is collected?”
Represent the problem as equal groups:
$5 + $5 + $5 + $5 + $5 + $5 = $30
Children may use repeated addition, skip counting or multiplication reasoning.
Give your child a class total and a proposed team size.
For example:
“There are 24 children. Each team needs 4 players. How many teams can be formed?”
Make groups of 4 until all 24 children have been placed:
6 teams can be formed.
The answer 6 represents teams, not children in each team.
The question may instead provide the number of teams.
Example:
“There are 24 children and 6 teams. How many children should be in each team?”
Share 24 equally among 6 teams:
There should be 4 children in each team.
Compare this problem with the previous example. The same quantities are involved, but the unknown is different.
Some practical division problems do not divide evenly.
Example:
“There are 26 children and teams need 4 players.”
Six complete teams can be formed, with 2 children remaining.
Ask what should happen in the real situation.
A remainder must be interpreted according to the situation. It should not be ignored automatically.
Use counters, pretend food pieces or play money to model equal sharing.
Example:
“Share $20 equally among 4 people.”
Each person receives $5.
Ask your child to explain:
Use a current or sample calendar to solve questions involving days, weeks and months.
To answer “How many days are left in the year?”:
Agree on whether the starting day is included before counting. Different interpretations can change the answer by one day.
The curriculum includes opportunities to explore equal grouping and sharing through First Nations Australian children’s instructive games, including the example of Yangamini from the Tiwi Island Peoples.
Use trusted educational resources that explain the game and its cultural context accurately.
Focus the mathematical discussion on:
Avoid changing, inventing or presenting cultural knowledge without an appropriate source. Keep the cultural context connected to the mathematical activity.
Ask your child to estimate or compare the answer with the quantities in the problem.
For example:
Encourage complete answers rather than isolated numbers.
Instead of:
6
write:
Six teams can be formed.
Instead of:
$9
write:
Each person receives $9.
Ask the child to explain what is happening to the quantities instead of relying only on words such as “total”, “left” or “each”.
Discuss which information is relevant to the question. Some practical problems may contain information that is not required.
Ask the child to represent the problem with objects or a drawing before choosing the operation.
Label these quantities separately and ask what the answer represents.
Include the dollar symbol in calculations and state the final answer as a money amount.
Return to the practical situation and decide what the leftover quantity means.
Whether to round up, round down, redistribute or report the remainder depends on the context.
Decide whether the starting day and ending day are included before beginning the count.
Ask the child to write a complete sentence that includes the unit and explains what the number represents.
Compare the answer with the original quantities and estimate what a sensible result should be.
Label household objects with whole-dollar prices and give your child a pretend budget.
Ask them to calculate totals, money remaining and the cost of several identical items.
Focus: AC9M2N06_E1 and AC9M2N06_E2.
Read short practical problems and ask your child to choose an operation before calculating.
Require a sentence explaining why the operation matches the situation.
Focus: Operation choice and justification.
Ask how much money would be collected if several people each contributed the same whole-dollar amount.
Use play money, repeated addition or skip counting.
Focus: Whole-dollar multiplication problems.
Choose a total number of players and a team size.
Ask how many complete teams can be formed and whether anyone remains.
Focus: Grouping division.
Choose a total number of players and a fixed number of teams.
Ask how many players should be placed in each team.
Focus: Sharing division.
Create practical grouping problems that leave one, two or three objects remaining.
Discuss what should happen to the remainder in each situation.
Focus: AC9M2N06_E3.
Use counters or safe food items to model sharing equally among several people.
Ask your child to explain whether the sharing is fair and what each person receives.
Focus: Equal sharing.
Use a calendar to calculate how many days remain in the current month.
Agree on whether today is included before counting.
Focus: Calendar modelling.
Count the remaining days in the current month and add the days in the remaining months.
Record the calculation and explain the counting convention used.
Focus: AC9M2N06_E4.
Choose one practical problem and represent it using materials, a diagram and a number sentence.
Compare how each representation shows the same relationship.
Focus: Mathematical modelling and communication.
The problem is asking me to find _____.
The information I know is _____.
The unknown quantity is _____.
I represented the problem by _____.
I chose addition because _____.
I chose subtraction because _____.
I chose multiplication because _____.
I chose division because _____.
My number sentence is _____.
I used the strategy _____.
The answer _____ represents _____.
There are _____ complete groups.
There are _____ remaining.
I decided to _____ with the remainder because _____.
My answer is reasonable because _____.
The solution to the practical problem is _____.
Use these questions to check whether your child understands the main ideas.
A child shows secure understanding when they can interpret the situation, choose and justify an operation, calculate accurately and communicate the solution using the correct context and unit.
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Mathematical modelling develops when children regularly solve meaningful problems and explain the connection between the calculation and the practical situation.
Use this simple routine:
Children who need additional support can revisit these earlier number, money, grouping and calculation topics.
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