Mini Minds Hub · Free printable
Best Buy Sleuth: Free Printable Worksheet for Year 8
- ForYear 8
- StageKey Stage 3
- CostFree
- FormatPrintable PDF
Best Buy Sleuth is a free printable maths worksheet for Year 8 (ages 12 to 13), in Key Stage 3. Children fill in a receipt table with unit prices, then use them to catch sneaky supermarket deals. It needs only a pencil, and a calculator is optional. Page 2 gives the grown-up notes, help ideas, a stretch task and the answers.
It comes from the Mini Minds Hub, the free library of printables from Jaques of London, the British games and toy company that has been making games for families since 1795. Print both pages, give page 1 to your child and keep page 2 for yourself. Black and white printing works well.
What is on the sheet
Children start with a table to fill in. It has columns for the item, the size, the price and the pence per 100 g. They then use their unit prices to answer numbered questions, such as which size is better value for the pasta and which for the cereal. There is space to write each answer. The sheet also practises multibuys and percentage changes, so children decide which deals are genuine savings.
- Item
- Size
- Price
- Pence per 100 g
- Which size is better value for the pasta, and which for the cereal?
Worked example: which rice is better value?
A 500 g bag of rice costs £1.20. A 2 kg bag costs £4.00. Which is better value?
This is a different question, with different items and numbers. It shows two ways to compare.
Method 1: pence per 100 g- Change the prices to pence: £1.20 is 120p and £4.00 is 400p.
- 500 g is 5 lots of 100 g. 120 ÷ 5 = 24p per 100 g.
- 2 kg is 2000 g, which is 20 lots of 100 g. 400 ÷ 20 = 20p per 100 g.
- Compare: 20p is less than 24p, so the 2 kg bag costs less for each 100 g.
- 500 g is half a kilogram, so double the price: 120p × 2 = 240p per kg.
- The 2 kg bag costs 400p, so halve it: 400 ÷ 2 = 200p per kg.
- Compare: 200p is less than 240p, so the 2 kg bag is better value.
Build the skills before you start
Convert the units
Practise changing kilograms to grams and pounds to pence. Try a few quick examples aloud, such as 2 kg or £3.50, before starting the sheet.
Divide to find one
Pick any price and size from a packet at home. Ask your child to divide the price by the number of 100 g lots to find the cost of 100 g.
Compare like with like
Remind children that two prices can only be compared fairly when they are in the same unit. Pence per 100 g gives every item the same measuring stick.
Read the offer carefully
Look at a real or made up offer together. Ask what you actually pay and what you actually get, before any sums begin.
Why do unit prices matter?
Supermarket shelf labels usually show a unit price, such as pence per 100 g or pounds per kilogram. This lets shoppers compare packs of different sizes fairly. A bigger pack has a bigger price, but that alone does not tell you whether it costs less for each gram. Dividing the price by the amount gives a fair comparison, and that is the skill at the heart of this sheet.
Deals can be worded in ways that sound better than they are. A multibuy such as 3 for 2 means you pay for two items and get three, so the saving needs working out. A percentage change tells you how much a price has gone up or down compared with its starting price. Good shoppers check the numbers instead of trusting the sticker.
Quick shopping maths facts
- 1 kilogram is the same as 1000 grams.
- A unit price lets you compare two packs of different sizes fairly.
- A 3 for 2 offer means you pay for two items and get three.
- 10% of an amount is one tenth of it.
- A bigger pack is not always the cheapest for each gram, so it is worth checking.
Skills and curriculum link
- Unit prices
- Percentage change
- Comparing deals
- Converting units
- Reasoning with money
Ideas for helping with the sheet
- Same units firstBefore comparing, make sure both amounts are in the same unit. Changing everything to pence and grams keeps the sums simple.
- Divide to find oneA unit price comes from dividing a price by an amount. Talk about what the answer means in words.
- Percentages as tenthsFinding 10% by dividing by 10 is a handy start. Other percentages can be built from it.
- Check the senseAsk whether an answer is sensible. If a small pack looks far cheaper than a big one, check the working.
Key words
- Unit priceThe cost of a standard amount, such as 100 g or 1 kg. It lets you compare different sizes fairly.
- PenceThe small units of UK money. There are 100 pence in £1.
- MultibuyAn offer where you buy several items together at a special price.
- Percentage changeHow much an amount has gone up or down, written as a percentage of the starting amount.
- Best valueThe choice that costs least for the same amount of product.
- ConvertChange an amount into a different unit without changing how much it is.
How to use it
- Print both pages. Page 1 is for your child. Keep page 2, which has the notes and answers.
- Read the table headings together. Check your child knows what each column is asking for.
- Let them fill in the table first, one row at a time. A calculator is optional.
- Use the unit prices to answer the questions. Ask, "How do you know?" The reason matters as much as the answer.
- Check with page 2 and come back another day to retry any tricky parts. Repeating a familiar sheet builds confidence.
Help, stretch and game ideas
If it feels too hard
Change all prices to pence first and write sizes in grams, so 1.5 kg becomes 1500 g. Fill in one row of the table at a time. Say aloud what you are dividing and why before you press any buttons.
To stretch confident children
Invent a sneaky deal of your own, such as a multibuy or a price change that sounds better than it is. Swap it with a partner and test it. They must prove whether it is a genuine saving.
Make it a game
Role play shoppers and shopkeepers. Shopkeepers pitch a deal with a price and a size. Shoppers must prove whether it is genuine by working out the unit price. Swap roles after each round.
Mistakes to watch for
Watch forA child compares the shelf prices only and picks the cheaper pack.
Try thisAsk what is different about the two sizes. Then work out the cost of the same amount for each pack.
Watch forA child divides a price in pounds by a size in grams, mixing units.
Try thisChange both to pence and grams first, then divide. Write the units next to every number.
Watch forA child works out a percentage change but forgets to apply it to the original price.
Try thisDraw a quick before and after line. Ask whether the new price should be higher or lower, and check the answer matches.
Talk about it
- How can you tell if a bigger pack is really a better deal?
- Why is it fairer to compare pence per 100 g than the shelf price?
- What is the sneakiest offer you have seen in a shop?
- If a deal says 3 for 2, what are you really paying?
- When might the cheapest unit price not be the best choice for a family?
- How could you check a deal quickly without a calculator?
Take it off the page
Shelf label hunt
On the next shop with an adult, look at the unit prices on shelf labels. Pick two similar items and predict which is better value before checking.
Deal designer poster
Design a poster for a pretend shop with one genuine deal and one sneaky deal. Ask a friend or family member to spot which is which.
Pocket money planner
Make a pretend shopping list with a small budget. Choose sizes and offers that give the most for the money, and explain each choice.
Who it is for
Parents
Sit beside your child for the first go, then let them lead. Short bursts work well. If they get stuck, ask them to change everything to pence and grams, then try one row of the table at a time.
Teachers
Use it as a starter, plenary, early finisher task, homework or table activity. It needs no preparation beyond printing. Page 2 has support and stretch ideas for mixed ability groups, which suits work on rates, proportion and percentages.
Home educators
Print it as part of a wider maths plan and pair it with real shopping trips or looking at packaging at home. It is free to print again for brothers and sisters, or for revision a few weeks later.
Where this fits in maths
Before this sheet, children work with multiplying and dividing decimals, converting between units, and finding percentages of amounts. Those skills make unit prices much easier, because every comparison relies on dividing and keeping units consistent.
After this sheet, children move on to wider work in ratio, proportion and rates of change. Comparing unit prices is an early example of working with a rate, and the same thinking is used later with speed, density and other everyday measures.
Questions parents and teachers ask
- What age is Best Buy Sleuth for?
It is written for Year 8 (ages 12 to 13), in Key Stage 3. It suits learners who are ready to apply division, units and percentages to real money choices. Confident Year 7 learners may enjoy it with some support.
- What will children practise?
Children practise comparing unit prices, multibuys and percentage changes to decide which supermarket deals are genuine savings. They also practise converting units and explaining their reasoning, which is useful in many other areas of maths.
- How do I use it?
Print both pages and give page 1 to your child. They complete the table first, then use their unit prices to answer the questions. A calculator is optional. Check against the answers on page 2 and talk through each choice.
- What if it feels too hard?
Let children change all prices to pence first and write 1.5 kg as 1500 g. Fill in the table one row at a time and say aloud what is being divided. Page 2 has more help for children who find it hard.
- Do children need a calculator?
No, a calculator is optional. Many children find it helpful for the division in the table, but the thinking matters more than the button pressing. Ask them to explain each step, whichever way they work.
- Is Best Buy Sleuth suitable for teachers to use in class?
Yes. Teachers can use it as a starter, plenary, early finisher task, homework or table activity. It needs no preparation beyond printing, and page 2 gives support and stretch ideas for mixed ability groups.
- Is this a screen free activity?
Yes. It is a screen free printable that needs only paper and a pencil, so it works well for quiet time, rainy days and school holidays. A calculator is optional if you want one.
Preview the full PDF
Made by Jaques of London, making games for families since 1795. A printable supports classroom learning and does not replace a teacher.