Lesson 3

Special Offers and Percentage Discounts

Topic: Number and Algebra - Financial Mathematics

Year Level: 8

ACARA (or NESA) Content description and Syllabus content indicator(s):

Investigate and calculate 'best buys', with and without the use of digital technologies(ACMNA174)

solve problems involving discounts, including calculating the percentage discount

Syllabus Working Mathematically Indicator(s):

› evaluate special offers, such as percentage discounts, 'buy-two-get-one-free', 'buy-one-get-another-at-half-price', etc, to determine how much is saved (Communicating, Problem Solving)

Learning Goals:

calculate with and without the use of digital technology the percentage discount on a given item
evaluate which types of discounts provide the best bargain by calculating the percentage discount
calculate and compare the price of discounted items

Materials/Resources required:

Printed Coupons (x3 for each pair)
Shopping Goodies: https://www.mathgoodies.com/articles/shopping-goodies
Duelling Discounts - http://threeacts.mrmeyer.com/duelingdiscounts/
Google Sheets Spreadsheets

Description of Lesson:

Orientation [5 mins] - Review homework findings from the previous lesson's task. Students to discuss what is the cheapest option for making their recipe. How could they save on cost if they had to make the recipe again? What strategies could they use? What would they have to consider?
Launch [10 mins] - Introducing terminology: 'percentage discounts', 'xx dollars off', 'BOGO', 'multi-buys', 'multi-save and conditional promotions'. Brainstorm the context of where these terms might be used, or have been seen by students. Teacher to present the question: "What makes a good deal?" (LIT)
Explore
Summarise [5 mins] - Teacher-led discussion recapping the key learning ideas and highlighting any patterns in the findings. (Use some examples from students' tables). (AFL)

Other resources/Lesson Worksheets

Activity 1 Resources from - Shopping Goodies: https://www.mathgoodies.com/articles/shopping-goodies

Homework/Follow up Tasks:

Students are to investigate the following situation:

Is a discount of 10% following a discount of 5% the same as a discount of 15%?
Students are to justify their answers with appropriate calculations
Determine the difference between the two discount situations.
Have students investigate if the order of discounts is important. i.e. is a discount of 5% following a discount of 10% the same as a discount of 10% following a discount of 5%? (LIT)

For further resources/extension tasks for this lesson, see Worksheet 3 "Extra Student Resources"