Money Math · Lesson Plan
Cost Comparison and Unit Cost
Which is the better buy — the bottle that costs less, or the bigger one that costs more? This lesson teaches students to answer that everyday grocery question by finding the unit cost (total cost divided by the number of units) and comparing. Students learn that the lower-priced item is not always the better value, then practice on real shopping scenarios.
For Teachers
Lesson at a glance
- Topic
- Money Math
- Grade Level
- Grades 5–8
- Resource Type
- Lesson + Worksheet
- Estimated Time
- 30–45 minutes
- Format
- Lesson + worksheet + answer key
- Materials
- Printable lesson, worksheet, answer key, calculator
What Students Learn
Learning objectives
- Define unit cost and cost comparison
- Calculate unit cost as total cost divided by number of units
- Round money amounts to the hundredths place
- Compare two products to identify the better buy
- Explain why the cheaper-priced item is not always the better value
Materials
What you’ll need
- Printed copies of the lesson and worksheet (one per student)
- Calculators
- Pencils
- Whiteboard or projector for worked examples
Key Terms
Vocabulary
- Unit cost
- The cost of one unit of an item — total cost divided by the number of units.
- Cost comparison
- Comparing two products to determine the better value.
- Better buy
- The product with the lower unit cost.
- Total cost
- The full price paid for an item.
- Unit
- A single measure of an item, such as one ounce.
- Round
- Adjust a number to a given place value, such as the hundredths place.
For Teachers
Lesson plan
Estimated time: one 30–45 minute class period.
Lesson sequence
- Introduction (5 min). Pose the juice example: a 20 oz bottle for $1.09 vs. a 32 oz bottle for $1.49. Which is the better buy?
- Teach unit cost (10 min). Work the formula unit cost = total cost ÷ number of units, round to the hundredths place, and compare. Show that the cheaper sticker price can be the more expensive option.
- Worksheet (15 min). Students find unit costs for five items and choose the better buy for five product pairs.
- Review (8 min). Check answers with the answer key and connect to real grocery shopping.
Assessment
Assess the completed worksheet against the included answer key.
Discussion
Discussion questions
- What is unit cost, and how do you calculate it?
- Why isn’t the item with the lower total price always the better buy?
- How does rounding to the hundredths place help when comparing prices?
- Where in real life would you use a cost comparison?
- When might you choose the more expensive unit cost on purpose?
Printable Lesson, Worksheet & Answer Key
Cost Comparison and Unit Cost — Lesson, Worksheet & Answer Key
A printable lesson with a worked grocery example, a 10-question unit-cost and better-buy worksheet, and a full answer key.
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