In size 6, a pair of Nike Free Runs costs \$100. In Size 8? \$100. Size 11? \$100, again. Is this fair? After all, people with small feet are paying the same as people with big feet, but they're getting less shoe!

In this lesson students will calculate unit rates to determine how much different sized shoes cost per ounce. They'll then use the unit rate to solve proportions to find out how much shoes would cost if Nike decided to charge by weight, and will discuss whether they should!

### Students will

• Calculate unit rate (\$/oz) for various sized shoes and discuss how the cost per ounces changes as size changes
• For a given cost per ounce, calculate how much different size shoes would cost if Nike charged by weight
• Discuss advantages and disadvantages of alternative pricing schemes

### Before you begin

It may be helpful if students know how to calculate a unit rate, e.g. use the price and weight to calculate the cost per ounce (\$/oz), though this is not necessary. In fact, you can easily use this lesson to introduce unit rates: both how to calculate them and why they're useful. Students should also be familiar with how to plot points on the coordinate plane.