Which Bed Bath & Beyond Coupon Should You Use?

 
Bed Bath & Beyond frequently sends out two different coupons to its customers.  One coupon is “20% off one single item.” and the other coupon is “$5 off any purchase of $15 or more.”
 

• Which coupon will save you the most money?

 

These questions may be useful in helping students down the problem solving path:

• Will both coupons always save you the same amount?
• How can we tell which coupon will save us more money?

 

Here are the two coupons that have been Photoshopped to remove the expiration dates and mailing addresses:

 

This coupon problem differs from the Michael’s coupon problem in one important way: it can be figured out before knowing what you are purchasing.  Here is how it breaks down:

• If you are spending less than $15 total, you cannot use the $5 off coupon so you should use the 20% as it is your only choice.
• If your highest priced item is $25, then both coupons will save you exactly $5 so you can use either coupon.
• If your highest priced item is between $15 and $25, then the 20% off coupon will save you less than $5 and you should use the $5 off coupon.
• If your highest priced item is more than $25, then the 20% off coupon will save you more than $5 and you should use the 20% off coupon.

It will likely be challenging for students to reach this conclusion without having scenarios to play out.  So, I have included four items from the Bed Bath & Beyond website for students to play around with.  Note that I have specifically chosen an item that is less than $15, an item that is between $15 and $25, a $25 item (whose price I PhotoShopped), and an item that is more than $25.

 

Consider having students start off by pretending to buy each of the items separately and determine which coupon is best.  If that isn’t enough to bring out the full list of when the coupons should be used, you could have them buy pairs of items and see how that affects their decision.  It might also come out during a discussion that the $5 off coupon is 33% off $15 but the more you spend, the lower the percentage you save.

As an extension, the reality is that Bed Bath and Beyond will accept multiple 20% off coupons in one purchase.  How will that affect your coupon choice?
 

Read about how Courtney implemented this problem using Socratic Circles (Socratic Seminar).  Really great job setting up the problem and then stepping back to let the students sort it out, especially when it would have been easier for her to step in and tell them what to do.
 
Below are 1 low, 2 medium, and 2 high work samples.  These were done as the first problem based lesson with an honors class.  What is notable is that the student who wrote the low work sample thoroughly understood the problem but didn’t understand what was expected in terms of a conclusion.  This is very common.  The medium work samples are a little better, but are still far from sufficient reasoning.  The high work samples are good but not perfect.  For example, one states a range of “$1 – $14” and “$15 – $24” which treats money as a set of whole numbers and does not address amounts such as $14.45.

• Low

• Medium

• Medium

• High

• High

 

• CCSS 7.RP.3 Use proportional relationships to solve multistep ratio and percent problems. Examples: simple interest, tax, markups and markdowns, gratuities and commissions, fees, percent increase and decrease, percent error.

 

• Bed Bath & Beyond