Real-Life Math Challenge
You’re planning a spaghetti dinner for eight people, but you have only $9 to spend.
You have the ingredient list and prices from five grocery stores. Your job is to compare the options, build a shopping plan, and explain your decisions.
Will buying everything at one store save you the most money—or should you split your shopping between stores?
What You Need
For this challenge, your dinner requires:
- 32 ounces of dry spaghetti
- 48 ounces of tomato-based pasta sauce
- 2 ounces of Parmesan cheese
You already have water, salt, and cooking equipment.
Your Grocery Price Guide
Each price buys one whole package. These are published online prices collected for this classroom activity; actual prices vary by location and date.
| Store | Spaghetti | Tomato-Based Pasta Sauce | Grated Parmesan |
|---|---|---|---|
| Walmart | Great Value: 16 oz — $1.24 | Great Value Traditional: 24 oz — $1.97 | Great Value: 8 oz — $3.00 |
| Target | Good & Gather Pot-Size: 16 oz — $0.99 | Good & Gather Traditional: 24 oz — $1.79 | Market Pantry: 8 oz — $3.19 |
| Safeway | Signature SELECT: 16 oz — $2.49 | Signature SELECT Marinara: 25 oz — $2.99 | Signature SELECT: 8 oz — $5.99 |
| ALDI | Reggano: 32 oz — $2.09 | Specially Selected Marinara: 24 oz — $4.39 | Reggano: 8 oz — $3.09 |
| Kroger | Kroger: 16 oz — $1.33 | Prego Three Cheese: 24 oz — $2.79 | Kroger: 8 oz — $3.49 |
Price sources: Walmart’s product listings. Target’s product listings. Safeway’s pasta bundle listing; the spaghetti uses its listed original price. ALDI’s product listings. Kroger’s product listings.
Shopping Rules
- Stay within $9 before tax.
- Buy enough of every ingredient.
- Pay for whole packages—you cannot buy just 2 ounces from an 8-ounce cheese container.
- You may shop at more than one store.
- Use only the prices in the table. Ignore coupons, memberships, and delivery fees.
- Treat all listed products as acceptable for this dinner. Judge value using cost and quantity.
Build Your Shopping Plan
Copy and complete this table in your response.
| Ingredient | Store chosen | Number of packages | Total ounces purchased | Total cost |
|---|---|---|---|---|
| Spaghetti | ||||
| Pasta sauce | ||||
| Parmesan |
Then calculate:
Total spent: $_____
Money remaining: $9 − $_____ = $_____
Purchase cost per person: Total spent ÷ 8 = $_____
Round the cost per person to the nearest cent.
Explain Your Decisions
After your shopping list, write at least five complete sentences answering these questions:
- Why did you choose each store? Use specific prices and quantities.
- Which spaghetti has the lowest cost per ounce? Does that choice also give you the lowest total cost for the amount you need?
- How much would your groceries cost if you bought everything at Target?
- How much does your plan save compared with that Target trip?
- What ingredients would you have left over?
Helpful formula:
Cost per ounce = Package price ÷ Ounces in the package
The Extra-Stop Challenge
Imagine each store you visit after your first store adds $1 in transportation costs.
Recalculate your total. Would you still split your shopping between stores, or would you change your plan? Explain using numbers.
Your goal: Make a shopping decision you can defend with math.
When you’re finished, check out the rest of our blog for more tips, ideas, and activities to help you learn and grow. Be sure to follow our classroom Instagram page for behind-the-scenes moments, project highlights, and fun updates. Let’s work together to make learning fun, exciting, and something you look forward to every day!
