The idea, step by step
Ask what the item must do
A consumer is someone who chooses goods or services. Before choosing, ask: Do I need it? Does it fit the money available? Will it do the job? The cheapest item is not helpful if it cannot do what is needed.
Compare fair choices
Check how much is in a pack and whether the items can be used. Do not buy extra things only because the pack looks large. Sharing, reusing or repairing something may meet a need without a new purchase. Use only facts given in the story when explaining a decision.
A common trap
Choosing a cheaper pack without checking whether it contains enough.
Instead: Compare the number needed as well as the total cost. An unsuitable purchase may not solve the problem.
See the thinking
Choose a suitable amount
You need 4 pencils and have 5 dollars. Pack A has 4 pencils for 4 dollars. Pack B has 2 pencils for 3 dollars. Which single pack meets both conditions?
- Pack A has all 4 needed pencils and costs no more than 5 dollars.
- Pack B has only 2 pencils, so one pack does not meet the need.
Reuse can be a choice
A project needs a clean box. You already have a suitable clean box. A new one costs 3 dollars. Give one sensible choice and its money effect.
- Check that the box you have meets the project's need.
- Reusing it costs nothing for this purchase.
Check your understanding
You need 2 erasers. A pack of 2 costs 3 dollars and a pack of 5 costs 6 dollars. Your budget is 4 dollars. Which pack fits?
Show answer
The pack of 2.
It has enough erasers and costs within the 4-dollar budget.
Your turn
6 questions · Work at your own pace.
Read the questions online
- You need a ruler. A suitable ruler costs 2 dollars and a toy costs 2 dollars. Which meets the stated need?
- You need 3 cups. Pack A has 3 cups for 4 dollars. Pack B has 2 cups for 3 dollars. Which single pack has enough cups?
- You have 5 dollars. An item costs 6 dollars. Does a bright sale sign make it fit your budget?
- You can reuse a suitable folder or buy a new one for 4 dollars. How much purchase money is kept by reusing it?
- You need 4 stickers. A pack of 4 costs 3 dollars. A pack of 8 costs 5 dollars. You have 3 dollars. Which fits the stated conditions?
- A friend chooses a 4-dollar notebook over a 3-dollar one because only the 4-dollar notebook has the page size their task needs. Is choosing the dearer one sensible if they have 5 dollars? Explain.
Read the worked solutions
- You need a ruler. A suitable ruler costs 2 dollars and a toy costs 2 dollars. Which meets the stated need?
Equal prices do not make the items equally useful for the need.
The ruler. - You need 3 cups. Pack A has 3 cups for 4 dollars. Pack B has 2 cups for 3 dollars. Which single pack has enough cups?
Three cups are needed; two are not enough.
Pack A. - You have 5 dollars. An item costs 6 dollars. Does a bright sale sign make it fit your budget?
The cost is still 1 dollar more than the money available.
No. - You can reuse a suitable folder or buy a new one for 4 dollars. How much purchase money is kept by reusing it?
Reusing the folder avoids the 4-dollar new purchase.
4 dollars. - You need 4 stickers. A pack of 4 costs 3 dollars. A pack of 8 costs 5 dollars. You have 3 dollars. Which fits the stated conditions?
It provides enough stickers and uses exactly the 3-dollar budget.
The pack of 4. - A friend chooses a 4-dollar notebook over a 3-dollar one because only the 4-dollar notebook has the page size their task needs. Is choosing the dearer one sensible if they have 5 dollars? Explain.
Suitability matters as well as price; 5 − 4 = 1 dollar remains.
Yes. It meets the task and fits the budget.
Curriculum reference & lesson scope
Australian Curriculum v9 and SA Curriculum Mathematics
Comparing prices; $1/$2 coins and notes; purchases; limited money and saving; needs/wants; consumer choices.
Official curriculum source ↗