Practice your discounts (Investigation)

Lesson

One of the most common places you can find percentages in real life is in stores. Some stores will offer you a choice between two sales when you are shopping. For instance they may offer you either 20% or or \$20 dollars off. This is when it comes in handy to be able to estimate percents in your head so you can make sure you are getting the better deal!

Objectives

To understand some ways applications are important in everyday life.
To practice with estimating percents.
To practice with calculating percents.

Materials

Printed out money
Printed out price labels
Markers
Printed out sales coupons
Tape
Calculator
Items from around your house/ classroom

Procedure

This activity has been written for pairs or small groups, but you can still complete it individually.

Print out the money, price labels, and sales coupons that appear below and then cut them out.
Collect several items from around your house or classroom and tape a price label to each one.
Place all of the sales coupons into a bag.
One person will be the cashier and the other(s) will be the customers.
The customer will collect all of the items they would like to buy in the store and then bring them to the cashier.
The cashier will then use their calculator to add up the total cost of the items and indicate to the customer the total amount.
The cashier will also shake up the bag of sales coupons and hold it out for the customer to select one.
Once the customer selects the sales coupon they should determine which discount would benefit them the most based on the total amount the cashier calculated. The discount may need to be converted to a percentage first.
While the customer is deciding which discount to take the cashier will use their calculator to determine which is actually the better deal. They will not tell the customer what is the right answer until after the customer has made their guess.
Once the customer has made their decision they will pay the cashier the amount they owe after the discount has been applied to the total. The cashier will let the customer know if they chose the right deal or not.

Questions

What method did you use to estimate which discount was more beneficial to you?
Compare with a friend! Did they use a different method to estimate which discount was more beneficial? Compare and contrast the methods you used.
What did you notice about the choice between the discounts of 20% off an \$20 off? Which is it more beneficial to use when the total amount you need to pay is a high number? Why?
Why do you think stores offer the option to choose between two different discount options?
In what other real life situations do you think understanding how to find percent of a quantity or comparing percentages with decimals and fractions would be useful? Brainstorm a few ideas on your own or with a partner.