Have you ever stood in the grocery store aisle, holding two boxes of cereal, trying to figure out which one is actually the better deal? One is cheaper but half the size… the other is double the price but looks like it might last longer. That’s real-world maths—and that’s exactly the kind of thinking we want our students doing in class.
When we teach unit pricing through real-life scenarios like grocery shopping, we’re not just ticking off curriculum boxes—we’re giving students skills they’ll use forever. And to kick off this topic in a way that immediately hooks students, I love starting with a hands-on inquiry.
A great way to spark their interest is to bring in real products with visible price tags. I’ve used three different-sized jars of peanut butter from the supermarket—each with a different price and size. Ask the class:
“Is the cheapest jar the best buy?”
Let them make predictions and debate! You’ll get opinions flying around the room—some who go straight for the cheapest, others who’ve picked up on value per 100g from their shopping trips. This is your perfect lead-in to teaching unit pricing—and they’re already engaged because it feels real.
Step-by-Step: Teaching Students to Calculate Unit Price
Once you’ve got your students on board with the why, it’s time to jump into the how. Here’s the explicit teaching breakdown I use:
✅ Step 1: Decide on a unit of measurement to compare
Usually per 100g, per 100mL, or per item. It’s important students know that comparisons need to use the same unit to be fair and accurate.
✅ Step 2: Divide the cost by the total number of units
This gives you the cost per 1g/mL/item. It’s simple division, but the context makes it meaningful.
✅ Step 3: Multiply by the comparison unit (e.g., 100)
Now we’re scaling it up to something familiar, like “per 100g” – which is what most supermarkets use.
✅ Step 4: Compare the cost per unit
Now it’s decision-making time. Students can now justify which product is the best buy based on maths, not just price tags.
Practice Time: Building Skills Through Progression
After your explicit teaching, it’s time for students to put their new skills to work. You’ll want to provide a good range of practice questions—from straightforward calculations to trickier comparisons involving different units (e.g., comparing something sold by weight to something sold by item).
Make sure the complexity increases gradually. I often include:
- Simple cost per 100g/mL questions
- Multi-pack vs bulk pack comparisons
- Prices with decimals (e.g., $3.75 or $1.98)
- Real catalogue excerpts to practise interpretation
Project Idea: Host a Dinner Party on a Budget
This is where the fun (and deeper thinking) really kicks in.
Wrap up the unit with a real-world project: students plan a dinner, BBQ or party. They get a set budget and a shopping list, and they have to make smart financial decisions using unit pricing comparisons. They justify their choices—and trust me, the debates about which drink or snack is the best value get intense!
It’s problem-solving, budgeting, and maths in action. And it makes the topic stick.
Want this Whole Lesson Ready to Print and Teach?
If this sounds like a lot to plan—don’t worry. I’ve created a LOW-PREP resource that gives you everything you need to teach unit pricing and best buys in an engaging, real-world way. Here’s what’s included:
- 📝 Teacher Notes to support your explicit instruction (definitions, steps, key vocab)
- ✍️ Guided and Independent Practice Worksheets with scaffolded progression
- 🛒 A realistic shopping catalogue created just for the unit—no need to collect your own
- 🎉 A Dinner Party Mini Project that lets students “go shopping” with a budget and make real financial decisions
- 💻 Available in printable and digital formats to suit your teaching style
This resource has saved me so much planning time and has made teaching financial maths actually fun. It’s one of those lessons that students remember (and keep bringing up next time they’re at the shops!).
Get it now!
